diff --git a/backend/src/apis/HttpRequest.ts b/backend/src/apis/HttpRequest.ts
index 4039e3a98..eff0c408a 100644
--- a/backend/src/apis/HttpRequest.ts
+++ b/backend/src/apis/HttpRequest.ts
@@ -1,16 +1,19 @@
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
 import axios from 'axios'
 
 import { backendLogger as logger } from '@/server/logger'
+import LogError from '@/server/LogError'
 
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 export const apiPost = async (url: string, payload: unknown): Promise<any> => {
-  logger.trace('POST: url=' + url + ' payload=' + payload)
+  logger.trace('POST', url, payload)
   return axios
     .post(url, payload)
     .then((result) => {
-      logger.trace('POST-Response: result=' + result)
+      logger.trace('POST-Response', result)
       if (result.status !== 200) {
-        throw new Error('HTTP Status Error ' + result.status)
+        throw new LogError('HTTP Status Error', result.status)
       }
       if (result.data.state !== 'success') {
         throw new Error(result.data.msg)
@@ -28,9 +31,9 @@ export const apiGet = async (url: string): Promise<any> => {
   return axios
     .get(url)
     .then((result) => {
-      logger.trace('GET-Response: result=' + result)
+      logger.trace('GET-Response', result)
       if (result.status !== 200) {
-        throw new Error('HTTP Status Error ' + result.status)
+        throw new LogError('HTTP Status Error', result.status)
       }
       if (!['success', 'warning'].includes(result.data.state)) {
         throw new Error(result.data.msg)
diff --git a/backend/src/apis/KlicktippController.ts b/backend/src/apis/KlicktippController.ts
index 824d40af2..fe9ad563a 100644
--- a/backend/src/apis/KlicktippController.ts
+++ b/backend/src/apis/KlicktippController.ts
@@ -1,3 +1,5 @@
+/* eslint-disable @typescript-eslint/no-unsafe-return */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 /* eslint-disable @typescript-eslint/explicit-module-boundary-types */
 import { KlicktippConnector } from './klicktippConnector'
diff --git a/backend/src/apis/klicktippConnector.ts b/backend/src/apis/klicktippConnector.ts
index b084112ae..0ff741604 100644
--- a/backend/src/apis/klicktippConnector.ts
+++ b/backend/src/apis/klicktippConnector.ts
@@ -1,3 +1,7 @@
+/* eslint-disable @typescript-eslint/no-unsafe-return */
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+/* eslint-disable @typescript-eslint/restrict-template-expressions */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 /* eslint-disable @typescript-eslint/explicit-module-boundary-types */
 import axios, { AxiosRequestConfig, Method } from 'axios'
diff --git a/backend/src/emails/sendEmailTranslated.test.ts b/backend/src/emails/sendEmailTranslated.test.ts
index 79ba1cd77..f3c75a7a6 100644
--- a/backend/src/emails/sendEmailTranslated.test.ts
+++ b/backend/src/emails/sendEmailTranslated.test.ts
@@ -1,3 +1,5 @@
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+/* eslint-disable @typescript-eslint/unbound-method */
 import { createTransport } from 'nodemailer'
 import { logger, i18n } from '@test/testSetup'
 import CONFIG from '@/config'
diff --git a/backend/src/emails/sendEmailTranslated.ts b/backend/src/emails/sendEmailTranslated.ts
index 9fa8af73f..d8ecd3d38 100644
--- a/backend/src/emails/sendEmailTranslated.ts
+++ b/backend/src/emails/sendEmailTranslated.ts
@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/restrict-template-expressions */
 import CONFIG from '@/config'
 import { backendLogger as logger } from '@/server/logger'
 import path from 'path'
diff --git a/backend/src/emails/sendEmailVariants.test.ts b/backend/src/emails/sendEmailVariants.test.ts
index 9f30a8ce1..21c10bdad 100644
--- a/backend/src/emails/sendEmailVariants.test.ts
+++ b/backend/src/emails/sendEmailVariants.test.ts
@@ -1,5 +1,8 @@
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
 /* eslint-disable @typescript-eslint/no-explicit-any */
-
+/* eslint-disable @typescript-eslint/no-unsafe-return */
+/* eslint-disable @typescript-eslint/no-unsafe-call */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
 import Decimal from 'decimal.js-light'
 import { testEnvironment } from '@test/helpers'
 import { logger, i18n as localization } from '@test/testSetup'
diff --git a/backend/src/federation/client/1_0/FederationClient.ts b/backend/src/federation/client/1_0/FederationClient.ts
index 1c0ec4996..d4ed5960b 100644
--- a/backend/src/federation/client/1_0/FederationClient.ts
+++ b/backend/src/federation/client/1_0/FederationClient.ts
@@ -1,3 +1,6 @@
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/no-unsafe-return */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
 import { gql } from 'graphql-request'
 import { backendLogger as logger } from '@/server/logger'
 import { Community as DbCommunity } from '@entity/Community'
diff --git a/backend/src/federation/client/1_1/FederationClient.ts b/backend/src/federation/client/1_1/FederationClient.ts
index 1c0ec4996..122fcf5dc 100644
--- a/backend/src/federation/client/1_1/FederationClient.ts
+++ b/backend/src/federation/client/1_1/FederationClient.ts
@@ -1,3 +1,6 @@
+/* eslint-disable @typescript-eslint/no-unsafe-return */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
 import { gql } from 'graphql-request'
 import { backendLogger as logger } from '@/server/logger'
 import { Community as DbCommunity } from '@entity/Community'
diff --git a/backend/src/federation/validateCommunities.test.ts b/backend/src/federation/validateCommunities.test.ts
index 4899a2987..bf9093b16 100644
--- a/backend/src/federation/validateCommunities.test.ts
+++ b/backend/src/federation/validateCommunities.test.ts
@@ -1,3 +1,7 @@
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/unbound-method */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+/* eslint-disable @typescript-eslint/no-unsafe-call */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 /* eslint-disable @typescript-eslint/explicit-module-boundary-types */
 
diff --git a/backend/src/federation/validateCommunities.ts b/backend/src/federation/validateCommunities.ts
index f5a0c50ac..157d83bb5 100644
--- a/backend/src/federation/validateCommunities.ts
+++ b/backend/src/federation/validateCommunities.ts
@@ -8,14 +8,14 @@ import { backendLogger as logger } from '@/server/logger'
 import { ApiVersionType } from './enum/apiVersionType'
 import LogError from '@/server/LogError'
 
-export async function startValidateCommunities(timerInterval: number): Promise<void> {
+export function startValidateCommunities(timerInterval: number): void {
   logger.info(
     `Federation: startValidateCommunities loop with an interval of ${timerInterval} ms...`,
   )
   // TODO: replace the timer-loop by an event-based communication to verify announced foreign communities
   // better to use setTimeout twice than setInterval once -> see https://javascript.info/settimeout-setinterval
   setTimeout(function run() {
-    validateCommunities()
+    void validateCommunities()
     setTimeout(run, timerInterval)
   }, timerInterval)
 }
@@ -27,8 +27,8 @@ export async function validateCommunities(): Promise<void> {
     .getMany()
 
   logger.debug(`Federation: found ${dbCommunities.length} dbCommunities`)
-  dbCommunities.forEach(async function (dbCom) {
-    logger.debug(`Federation: dbCom: ${JSON.stringify(dbCom)}`)
+  for (const dbCom of dbCommunities) {
+    logger.debug('Federation: dbCom', dbCom)
     const apiValueStrings: string[] = Object.values(ApiVersionType)
     logger.debug(`suppported ApiVersions=`, apiValueStrings)
     if (apiValueStrings.includes(dbCom.apiVersion)) {
@@ -38,11 +38,13 @@ export async function validateCommunities(): Promise<void> {
       try {
         const pubKey = await invokeVersionedRequestGetPublicKey(dbCom)
         logger.info(
-          `Federation: received publicKey=${pubKey} from endpoint=${dbCom.endPoint}/${dbCom.apiVersion}`,
+          'Federation: received publicKey from endpoint',
+          pubKey,
+          `${dbCom.endPoint}/${dbCom.apiVersion}`,
         )
         if (pubKey && pubKey === dbCom.publicKey.toString('hex')) {
           logger.info(`Federation: matching publicKey:  ${pubKey}`)
-          DbCommunity.update({ id: dbCom.id }, { verifiedAt: new Date() })
+          await DbCommunity.update({ id: dbCom.id }, { verifiedAt: new Date() })
           logger.debug(`Federation: updated dbCom:  ${JSON.stringify(dbCom)}`)
         }
         /*
@@ -58,10 +60,11 @@ export async function validateCommunities(): Promise<void> {
       }
     } else {
       logger.warn(
-        `Federation: dbCom: ${dbCom.id} with unsupported apiVersion=${dbCom.apiVersion}; supported versions=${apiValueStrings}`,
+        `Federation: dbCom: ${dbCom.id} with unsupported apiVersion=${dbCom.apiVersion}; supported versions`,
+        apiValueStrings,
       )
     }
-  })
+  }
 }
 
 function isLogError(err: unknown) {
diff --git a/backend/src/graphql/arg/ContributionLinkArgs.ts b/backend/src/graphql/arg/ContributionLinkArgs.ts
index 7344a28ff..cf0465501 100644
--- a/backend/src/graphql/arg/ContributionLinkArgs.ts
+++ b/backend/src/graphql/arg/ContributionLinkArgs.ts
@@ -22,7 +22,7 @@ export default class ContributionLinkArgs {
   validTo?: string | null
 
   @Field(() => Decimal, { nullable: true })
-  maxAmountPerMonth: Decimal | null
+  maxAmountPerMonth?: Decimal | null
 
   @Field(() => Int)
   maxPerCycle: number
diff --git a/backend/src/graphql/arg/ContributionMessageArgs.ts b/backend/src/graphql/arg/ContributionMessageArgs.ts
index dd75baed0..0e573bd36 100644
--- a/backend/src/graphql/arg/ContributionMessageArgs.ts
+++ b/backend/src/graphql/arg/ContributionMessageArgs.ts
@@ -1,9 +1,9 @@
-import { ArgsType, Field, InputType } from 'type-graphql'
+import { ArgsType, Field, ID, InputType } from 'type-graphql'
 
 @InputType()
 @ArgsType()
 export default class ContributionMessageArgs {
-  @Field(() => Number)
+  @Field(() => ID)
   contributionId: number
 
   @Field(() => String)
diff --git a/backend/src/graphql/arg/CreateUserArgs.ts b/backend/src/graphql/arg/CreateUserArgs.ts
index af915b91a..56acfd63d 100644
--- a/backend/src/graphql/arg/CreateUserArgs.ts
+++ b/backend/src/graphql/arg/CreateUserArgs.ts
@@ -11,11 +11,11 @@ export default class CreateUserArgs {
   @Field(() => String)
   lastName: string
 
-  @Field(() => String)
-  language?: string // Will default to DEFAULT_LANGUAGE
+  @Field(() => String, { nullable: true })
+  language?: string | null
 
   @Field(() => Int, { nullable: true })
-  publisherId: number
+  publisherId?: number | null
 
   @Field(() => String, { nullable: true })
   redeemCode?: string | null
diff --git a/backend/src/graphql/arg/Paginated.ts b/backend/src/graphql/arg/Paginated.ts
index 97326caf2..290dba337 100644
--- a/backend/src/graphql/arg/Paginated.ts
+++ b/backend/src/graphql/arg/Paginated.ts
@@ -1,3 +1,4 @@
+/* eslint-disable type-graphql/invalid-nullable-input-type */
 import { ArgsType, Field, Int } from 'type-graphql'
 import { Order } from '@enum/Order'
 
diff --git a/backend/src/graphql/arg/SearchUsersArgs.ts b/backend/src/graphql/arg/SearchUsersArgs.ts
index 38057762d..39996efca 100644
--- a/backend/src/graphql/arg/SearchUsersArgs.ts
+++ b/backend/src/graphql/arg/SearchUsersArgs.ts
@@ -7,11 +7,14 @@ export default class SearchUsersArgs {
   searchText: string
 
   @Field(() => Int, { nullable: true })
+  // eslint-disable-next-line type-graphql/invalid-nullable-input-type
   currentPage?: number
 
   @Field(() => Int, { nullable: true })
+  // eslint-disable-next-line type-graphql/invalid-nullable-input-type
   pageSize?: number
 
+  // eslint-disable-next-line type-graphql/wrong-decorator-signature
   @Field(() => SearchUsersFilters, { nullable: true, defaultValue: null })
-  filters: SearchUsersFilters
+  filters?: SearchUsersFilters | null
 }
diff --git a/backend/src/graphql/arg/SearchUsersFilters.ts b/backend/src/graphql/arg/SearchUsersFilters.ts
index dc19d456c..efcdfa00d 100644
--- a/backend/src/graphql/arg/SearchUsersFilters.ts
+++ b/backend/src/graphql/arg/SearchUsersFilters.ts
@@ -3,8 +3,8 @@ import { Field, InputType } from 'type-graphql'
 @InputType()
 export default class SearchUsersFilters {
   @Field(() => Boolean, { nullable: true, defaultValue: null })
-  byActivated: boolean
+  byActivated?: boolean | null
 
   @Field(() => Boolean, { nullable: true, defaultValue: null })
-  byDeleted: boolean
+  byDeleted?: boolean | null
 }
diff --git a/backend/src/graphql/arg/TransactionLinkFilters.ts b/backend/src/graphql/arg/TransactionLinkFilters.ts
index 291d244c3..13d630d17 100644
--- a/backend/src/graphql/arg/TransactionLinkFilters.ts
+++ b/backend/src/graphql/arg/TransactionLinkFilters.ts
@@ -1,13 +1,14 @@
+/* eslint-disable type-graphql/invalid-nullable-input-type */
 import { Field, InputType } from 'type-graphql'
 
 @InputType()
 export default class TransactionLinkFilters {
   @Field(() => Boolean, { nullable: true })
-  withDeleted: boolean
+  withDeleted?: boolean
 
   @Field(() => Boolean, { nullable: true })
-  withExpired: boolean
+  withExpired?: boolean
 
   @Field(() => Boolean, { nullable: true })
-  withRedeemed: boolean
+  withRedeemed?: boolean
 }
diff --git a/backend/src/graphql/arg/UnsecureLoginArgs.ts b/backend/src/graphql/arg/UnsecureLoginArgs.ts
index ac69e7441..a2a7bb683 100644
--- a/backend/src/graphql/arg/UnsecureLoginArgs.ts
+++ b/backend/src/graphql/arg/UnsecureLoginArgs.ts
@@ -9,5 +9,5 @@ export default class UnsecureLoginArgs {
   password: string
 
   @Field(() => Int, { nullable: true })
-  publisherId: number
+  publisherId?: number | null
 }
diff --git a/backend/src/graphql/arg/UpdateUserInfosArgs.ts b/backend/src/graphql/arg/UpdateUserInfosArgs.ts
index b45539487..985d3fed6 100644
--- a/backend/src/graphql/arg/UpdateUserInfosArgs.ts
+++ b/backend/src/graphql/arg/UpdateUserInfosArgs.ts
@@ -1,4 +1,4 @@
-import { ArgsType, Field } from 'type-graphql'
+import { ArgsType, Field, Int } from 'type-graphql'
 
 @ArgsType()
 export default class UpdateUserInfosArgs {
@@ -11,8 +11,8 @@ export default class UpdateUserInfosArgs {
   @Field({ nullable: true })
   language?: string
 
-  @Field({ nullable: true })
-  publisherId?: number
+  @Field(() => Int, { nullable: true })
+  publisherId?: number | null
 
   @Field({ nullable: true })
   password?: string
diff --git a/backend/src/graphql/directive/isAuthorized.ts b/backend/src/graphql/directive/isAuthorized.ts
index 59daa89f1..709f470d4 100644
--- a/backend/src/graphql/directive/isAuthorized.ts
+++ b/backend/src/graphql/directive/isAuthorized.ts
@@ -1,3 +1,5 @@
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/no-unsafe-call */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 
 import { AuthChecker } from 'type-graphql'
diff --git a/backend/src/graphql/model/Balance.ts b/backend/src/graphql/model/Balance.ts
index f04b235ee..78844c5ee 100644
--- a/backend/src/graphql/model/Balance.ts
+++ b/backend/src/graphql/model/Balance.ts
@@ -1,4 +1,4 @@
-import { ObjectType, Field } from 'type-graphql'
+import { ObjectType, Field, Int } from 'type-graphql'
 import Decimal from 'decimal.js-light'
 
 @ObjectType()
@@ -19,14 +19,14 @@ export class Balance {
   @Field(() => Decimal)
   balance: Decimal
 
-  @Field(() => Number, { nullable: true })
+  @Field(() => Int, { nullable: true })
   balanceGDT: number | null
 
   // the count of all transactions
-  @Field(() => Number)
+  @Field(() => Int)
   count: number
 
   // the count of transaction links
-  @Field(() => Number)
+  @Field(() => Int)
   linkCount: number
 }
diff --git a/backend/src/graphql/model/Community.ts b/backend/src/graphql/model/Community.ts
index 466028d00..bf8784be2 100644
--- a/backend/src/graphql/model/Community.ts
+++ b/backend/src/graphql/model/Community.ts
@@ -1,6 +1,8 @@
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 /* eslint-disable @typescript-eslint/explicit-module-boundary-types */
-import { ObjectType, Field } from 'type-graphql'
+import { ObjectType, Field, ID } from 'type-graphql'
 
 @ObjectType()
 export class Community {
@@ -14,7 +16,7 @@ export class Community {
     }
   }
 
-  @Field(() => Number)
+  @Field(() => ID)
   id: number
 
   @Field(() => String)
diff --git a/backend/src/graphql/model/CommunityStatistics.ts b/backend/src/graphql/model/CommunityStatistics.ts
index 87ef595af..4864b630d 100644
--- a/backend/src/graphql/model/CommunityStatistics.ts
+++ b/backend/src/graphql/model/CommunityStatistics.ts
@@ -1,9 +1,9 @@
-import { ObjectType, Field } from 'type-graphql'
+import { ObjectType, Field, Int } from 'type-graphql'
 import Decimal from 'decimal.js-light'
 
 @ObjectType()
 export class DynamicStatisticsFields {
-  @Field(() => Number)
+  @Field(() => Int)
   activeUsers: number
 
   @Field(() => Decimal)
@@ -15,13 +15,13 @@ export class DynamicStatisticsFields {
 
 @ObjectType()
 export class CommunityStatistics {
-  @Field(() => Number)
+  @Field(() => Int)
   allUsers: number
 
-  @Field(() => Number)
+  @Field(() => Int)
   totalUsers: number
 
-  @Field(() => Number)
+  @Field(() => Int)
   deletedUsers: number
 
   @Field(() => Decimal)
diff --git a/backend/src/graphql/model/Contribution.ts b/backend/src/graphql/model/Contribution.ts
index b966b714e..4345a79a6 100644
--- a/backend/src/graphql/model/Contribution.ts
+++ b/backend/src/graphql/model/Contribution.ts
@@ -1,4 +1,4 @@
-import { ObjectType, Field, Int } from 'type-graphql'
+import { ObjectType, Field, Int, ID } from 'type-graphql'
 import Decimal from 'decimal.js-light'
 import { Contribution as dbContribution } from '@entity/Contribution'
 import { User } from '@entity/User'
@@ -23,7 +23,7 @@ export class Contribution {
     this.deletedBy = contribution.deletedBy
   }
 
-  @Field(() => Number)
+  @Field(() => ID)
   id: number
 
   @Field(() => String, { nullable: true })
@@ -44,13 +44,13 @@ export class Contribution {
   @Field(() => Date, { nullable: true })
   confirmedAt: Date | null
 
-  @Field(() => Number, { nullable: true })
+  @Field(() => ID, { nullable: true })
   confirmedBy: number | null
 
   @Field(() => Date, { nullable: true })
   deniedAt: Date | null
 
-  @Field(() => Number, { nullable: true })
+  @Field(() => ID, { nullable: true })
   deniedBy: number | null
 
   @Field(() => Date, { nullable: true })
@@ -62,7 +62,7 @@ export class Contribution {
   @Field(() => Date)
   contributionDate: Date
 
-  @Field(() => Number)
+  @Field(() => Int)
   messagesCount: number
 
   @Field(() => String)
diff --git a/backend/src/graphql/model/ContributionLink.ts b/backend/src/graphql/model/ContributionLink.ts
index 9fe9eccd6..0a81db38d 100644
--- a/backend/src/graphql/model/ContributionLink.ts
+++ b/backend/src/graphql/model/ContributionLink.ts
@@ -1,4 +1,4 @@
-import { ObjectType, Field, Int } from 'type-graphql'
+import { ObjectType, Field, Int, ID } from 'type-graphql'
 import Decimal from 'decimal.js-light'
 import { ContributionLink as dbContributionLink } from '@entity/ContributionLink'
 import CONFIG from '@/config'
@@ -21,7 +21,7 @@ export class ContributionLink {
     this.link = CONFIG.COMMUNITY_REDEEM_CONTRIBUTION_URL.replace(/{code}/g, this.code)
   }
 
-  @Field(() => Number)
+  @Field(() => ID)
   id: number
 
   @Field(() => Decimal)
diff --git a/backend/src/graphql/model/ContributionLinkList.ts b/backend/src/graphql/model/ContributionLinkList.ts
index 412d0bf7b..d2c347b27 100644
--- a/backend/src/graphql/model/ContributionLinkList.ts
+++ b/backend/src/graphql/model/ContributionLinkList.ts
@@ -1,4 +1,4 @@
-import { ObjectType, Field } from 'type-graphql'
+import { ObjectType, Field, Int } from 'type-graphql'
 import { ContributionLink } from '@model/ContributionLink'
 
 @ObjectType()
@@ -6,6 +6,6 @@ export class ContributionLinkList {
   @Field(() => [ContributionLink])
   links: ContributionLink[]
 
-  @Field(() => Number)
+  @Field(() => Int)
   count: number
 }
diff --git a/backend/src/graphql/model/ContributionMessage.ts b/backend/src/graphql/model/ContributionMessage.ts
index d757db136..bdcfc093d 100644
--- a/backend/src/graphql/model/ContributionMessage.ts
+++ b/backend/src/graphql/model/ContributionMessage.ts
@@ -1,4 +1,4 @@
-import { Field, ObjectType } from 'type-graphql'
+import { Field, ID, Int, ObjectType } from 'type-graphql'
 import { ContributionMessage as DbContributionMessage } from '@entity/ContributionMessage'
 import { User } from '@entity/User'
 
@@ -16,7 +16,7 @@ export class ContributionMessage {
     this.isModerator = contributionMessage.isModerator
   }
 
-  @Field(() => Number)
+  @Field(() => ID)
   id: number
 
   @Field(() => String)
@@ -26,7 +26,7 @@ export class ContributionMessage {
   createdAt: Date
 
   @Field(() => Date, { nullable: true })
-  updatedAt?: Date | null
+  updatedAt: Date | null
 
   @Field(() => String)
   type: string
@@ -37,7 +37,7 @@ export class ContributionMessage {
   @Field(() => String, { nullable: true })
   userLastName: string | null
 
-  @Field(() => Number, { nullable: true })
+  @Field(() => ID, { nullable: true })
   userId: number | null
 
   @Field(() => Boolean)
@@ -45,7 +45,7 @@ export class ContributionMessage {
 }
 @ObjectType()
 export class ContributionMessageListResult {
-  @Field(() => Number)
+  @Field(() => Int)
   count: number
 
   @Field(() => [ContributionMessage])
diff --git a/backend/src/graphql/model/GdtEntry.ts b/backend/src/graphql/model/GdtEntry.ts
index 43529fb06..01fb308ae 100644
--- a/backend/src/graphql/model/GdtEntry.ts
+++ b/backend/src/graphql/model/GdtEntry.ts
@@ -1,6 +1,8 @@
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 /* eslint-disable @typescript-eslint/explicit-module-boundary-types */
-import { ObjectType, Field } from 'type-graphql'
+import { ObjectType, Field, Float, ID } from 'type-graphql'
 import { GdtEntryType } from '@enum/GdtEntryType'
 
 @ObjectType()
@@ -19,10 +21,10 @@ export class GdtEntry {
     this.gdt = json.gdt
   }
 
-  @Field(() => Number)
+  @Field(() => ID)
   id: number
 
-  @Field(() => Number)
+  @Field(() => Float)
   amount: number
 
   @Field(() => String)
@@ -40,15 +42,15 @@ export class GdtEntry {
   @Field(() => GdtEntryType)
   gdtEntryType: GdtEntryType
 
-  @Field(() => Number)
+  @Field(() => Float)
   factor: number
 
-  @Field(() => Number)
+  @Field(() => Float)
   amount2: number
 
-  @Field(() => Number)
+  @Field(() => Float)
   factor2: number
 
-  @Field(() => Number)
+  @Field(() => Float)
   gdt: number
 }
diff --git a/backend/src/graphql/model/GdtEntryList.ts b/backend/src/graphql/model/GdtEntryList.ts
index 9d529b6f3..95d118cf3 100644
--- a/backend/src/graphql/model/GdtEntryList.ts
+++ b/backend/src/graphql/model/GdtEntryList.ts
@@ -1,7 +1,10 @@
+/* eslint-disable @typescript-eslint/no-unsafe-call */
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 /* eslint-disable @typescript-eslint/explicit-module-boundary-types */
 import { GdtEntry } from './GdtEntry'
-import { ObjectType, Field } from 'type-graphql'
+import { ObjectType, Field, Int } from 'type-graphql'
 
 @ObjectType()
 export class GdtEntryList {
@@ -16,15 +19,15 @@ export class GdtEntryList {
   @Field(() => String)
   state: string
 
-  @Field(() => Number)
+  @Field(() => Int)
   count: number
 
   @Field(() => [GdtEntry], { nullable: true })
-  gdtEntries?: GdtEntry[]
+  gdtEntries: GdtEntry[] | null
 
-  @Field(() => Number)
+  @Field(() => Int)
   gdtSum: number
 
-  @Field(() => Number)
+  @Field(() => Int)
   timeUsed: number
 }
diff --git a/backend/src/graphql/model/KlickTipp.ts b/backend/src/graphql/model/KlickTipp.ts
index a7dd9eead..059c7874d 100644
--- a/backend/src/graphql/model/KlickTipp.ts
+++ b/backend/src/graphql/model/KlickTipp.ts
@@ -1,4 +1,5 @@
 /* eslint-disable @typescript-eslint/no-explicit-any */
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
 /* eslint-disable @typescript-eslint/explicit-module-boundary-types */
 import { ObjectType, Field } from 'type-graphql'
 
diff --git a/backend/src/graphql/model/Transaction.ts b/backend/src/graphql/model/Transaction.ts
index a7329bcef..6f480000b 100644
--- a/backend/src/graphql/model/Transaction.ts
+++ b/backend/src/graphql/model/Transaction.ts
@@ -1,4 +1,4 @@
-import { ObjectType, Field } from 'type-graphql'
+import { ObjectType, Field, ID } from 'type-graphql'
 import { Decay } from './Decay'
 import { Transaction as dbTransaction } from '@entity/Transaction'
 import Decimal from 'decimal.js-light'
@@ -41,19 +41,19 @@ export class Transaction {
     this.memo = transaction.memo
     this.creationDate = transaction.creationDate
     this.linkedUser = linkedUser
-    this.linkedTransactionId = transaction.linkedTransactionId
+    this.linkedTransactionId = transaction.linkedTransactionId || null
     this.linkId = transaction.contribution
       ? transaction.contribution.contributionLinkId
-      : transaction.transactionLinkId
+      : transaction.transactionLinkId || null
   }
 
-  @Field(() => Number)
+  @Field(() => ID)
   id: number
 
   @Field(() => User)
   user: User
 
-  @Field(() => Number, { nullable: true })
+  @Field(() => ID, { nullable: true })
   previous: number | null
 
   @Field(() => TransactionTypeId)
@@ -80,10 +80,10 @@ export class Transaction {
   @Field(() => User, { nullable: true })
   linkedUser: User | null
 
-  @Field(() => Number, { nullable: true })
-  linkedTransactionId?: number | null
+  @Field(() => ID, { nullable: true })
+  linkedTransactionId: number | null
 
   // Links to the TransactionLink/ContributionLink when transaction was created by a link
-  @Field(() => Number, { nullable: true })
-  linkId?: number | null
+  @Field(() => ID, { nullable: true })
+  linkId: number | null
 }
diff --git a/backend/src/graphql/model/TransactionLink.ts b/backend/src/graphql/model/TransactionLink.ts
index 416527ec9..4c10c79d8 100644
--- a/backend/src/graphql/model/TransactionLink.ts
+++ b/backend/src/graphql/model/TransactionLink.ts
@@ -1,4 +1,4 @@
-import { ObjectType, Field, Int } from 'type-graphql'
+import { ObjectType, Field, Int, ID } from 'type-graphql'
 import Decimal from 'decimal.js-light'
 import { TransactionLink as dbTransactionLink } from '@entity/TransactionLink'
 import { User } from './User'
@@ -21,7 +21,7 @@ export class TransactionLink {
     this.link = CONFIG.COMMUNITY_REDEEM_URL.replace(/{code}/g, this.code)
   }
 
-  @Field(() => Number)
+  @Field(() => ID)
   id: number
 
   @Field(() => User)
diff --git a/backend/src/graphql/model/UnconfirmedContribution.ts b/backend/src/graphql/model/UnconfirmedContribution.ts
index c42b4fd11..068505594 100644
--- a/backend/src/graphql/model/UnconfirmedContribution.ts
+++ b/backend/src/graphql/model/UnconfirmedContribution.ts
@@ -1,4 +1,4 @@
-import { ObjectType, Field, Int } from 'type-graphql'
+import { ObjectType, Field, Int, ID } from 'type-graphql'
 import Decimal from 'decimal.js-light'
 import { Contribution } from '@entity/Contribution'
 import { User } from '@entity/User'
@@ -24,12 +24,12 @@ export class UnconfirmedContribution {
   firstName: string
 
   @Field(() => Int)
-  id?: number
+  id: number
 
   @Field(() => String)
   lastName: string
 
-  @Field(() => Number)
+  @Field(() => ID)
   userId: number
 
   @Field(() => String)
@@ -44,7 +44,7 @@ export class UnconfirmedContribution {
   @Field(() => Decimal)
   amount: Decimal
 
-  @Field(() => Number, { nullable: true })
+  @Field(() => ID, { nullable: true })
   moderator: number | null
 
   @Field(() => [Decimal])
@@ -53,6 +53,6 @@ export class UnconfirmedContribution {
   @Field(() => String)
   state: string
 
-  @Field(() => Number)
+  @Field(() => Int)
   messageCount: number
 }
diff --git a/backend/src/graphql/model/User.ts b/backend/src/graphql/model/User.ts
index b4fdcae4f..bf973d047 100644
--- a/backend/src/graphql/model/User.ts
+++ b/backend/src/graphql/model/User.ts
@@ -1,4 +1,4 @@
-import { ObjectType, Field } from 'type-graphql'
+import { ObjectType, Field, ID, Int } from 'type-graphql'
 import { KlickTipp } from './KlickTipp'
 import { User as dbUser } from '@entity/User'
 import { UserContact } from './UserContact'
@@ -28,21 +28,21 @@ export class User {
     this.hideAmountGDT = user.hideAmountGDT
   }
 
-  @Field(() => Number)
+  @Field(() => ID)
   id: number
 
   @Field(() => String)
   gradidoID: string
 
   @Field(() => String, { nullable: true })
-  alias?: string
+  alias: string | null
 
-  @Field(() => Number, { nullable: true })
+  @Field(() => ID, { nullable: true })
   emailId: number | null
 
   // TODO privacy issue here
   @Field(() => String, { nullable: true })
-  email: string
+  email: string | null
 
   @Field(() => UserContact)
   emailContact: UserContact
@@ -72,7 +72,7 @@ export class User {
   hideAmountGDT: boolean
 
   // This is not the users publisherId, but the one of the users who recommend him
-  @Field(() => Number, { nullable: true })
+  @Field(() => Int, { nullable: true })
   publisherId: number | null
 
   @Field(() => Date, { nullable: true })
diff --git a/backend/src/graphql/model/UserAdmin.ts b/backend/src/graphql/model/UserAdmin.ts
index 08dc405ac..e4e3a8315 100644
--- a/backend/src/graphql/model/UserAdmin.ts
+++ b/backend/src/graphql/model/UserAdmin.ts
@@ -1,4 +1,4 @@
-import { ObjectType, Field, Int } from 'type-graphql'
+import { ObjectType, Field, Int, ID } from 'type-graphql'
 import Decimal from 'decimal.js-light'
 import { User } from '@entity/User'
 
@@ -17,7 +17,7 @@ export class UserAdmin {
     this.isAdmin = user.isAdmin
   }
 
-  @Field(() => Number)
+  @Field(() => ID)
   userId: number
 
   @Field(() => String)
@@ -39,10 +39,10 @@ export class UserAdmin {
   hasElopage: boolean
 
   @Field(() => Date, { nullable: true })
-  deletedAt?: Date | null
+  deletedAt: Date | null
 
   @Field(() => String, { nullable: true })
-  emailConfirmationSend?: string
+  emailConfirmationSend: string | null
 
   @Field(() => Date, { nullable: true })
   isAdmin: Date | null
diff --git a/backend/src/graphql/model/UserContact.ts b/backend/src/graphql/model/UserContact.ts
index 796c7f5f3..b62e746a2 100644
--- a/backend/src/graphql/model/UserContact.ts
+++ b/backend/src/graphql/model/UserContact.ts
@@ -1,4 +1,4 @@
-import { ObjectType, Field } from 'type-graphql'
+import { ObjectType, Field, ID, Int } from 'type-graphql'
 import { UserContact as dbUserContact } from '@entity/UserContact'
 
 @ObjectType()
@@ -18,13 +18,13 @@ export class UserContact {
     this.deletedAt = userContact.deletedAt
   }
 
-  @Field(() => Number)
+  @Field(() => ID)
   id: number
 
   @Field(() => String)
   type: string
 
-  @Field(() => Number)
+  @Field(() => ID)
   userId: number
 
   @Field(() => String)
@@ -33,10 +33,10 @@ export class UserContact {
   // @Field(() => BigInt, { nullable: true })
   // emailVerificationCode: BigInt | null
 
-  @Field(() => Number, { nullable: true })
+  @Field(() => Int, { nullable: true })
   emailOptInTypeId: number | null
 
-  @Field(() => Number, { nullable: true })
+  @Field(() => Int, { nullable: true })
   emailResendCount: number | null
 
   @Field(() => Boolean)
diff --git a/backend/src/graphql/resolver/BalanceResolver.ts b/backend/src/graphql/resolver/BalanceResolver.ts
index 65cccf4d4..18aed5ae6 100644
--- a/backend/src/graphql/resolver/BalanceResolver.ts
+++ b/backend/src/graphql/resolver/BalanceResolver.ts
@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/restrict-template-expressions */
 import Decimal from 'decimal.js-light'
 import { Resolver, Query, Ctx, Authorized } from 'type-graphql'
 import { getCustomRepository } from '@dbTools/typeorm'
diff --git a/backend/src/graphql/resolver/CommunityResolver.test.ts b/backend/src/graphql/resolver/CommunityResolver.test.ts
index cb916e47c..95f2ec5dd 100644
--- a/backend/src/graphql/resolver/CommunityResolver.test.ts
+++ b/backend/src/graphql/resolver/CommunityResolver.test.ts
@@ -1,3 +1,6 @@
+/* eslint-disable @typescript-eslint/no-unsafe-call */
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/unbound-method */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 /* eslint-disable @typescript-eslint/explicit-module-boundary-types */
 
diff --git a/backend/src/graphql/resolver/CommunityResolver.ts b/backend/src/graphql/resolver/CommunityResolver.ts
index f56254e1f..4cd0c8f69 100644
--- a/backend/src/graphql/resolver/CommunityResolver.ts
+++ b/backend/src/graphql/resolver/CommunityResolver.ts
@@ -9,7 +9,7 @@ import CONFIG from '@/config'
 export class CommunityResolver {
   @Authorized([RIGHTS.GET_COMMUNITY_INFO])
   @Query(() => Community)
-  async getCommunityInfo(): Promise<Community> {
+  getCommunityInfo(): Community {
     return new Community({
       name: CONFIG.COMMUNITY_NAME,
       description: CONFIG.COMMUNITY_DESCRIPTION,
@@ -20,7 +20,7 @@ export class CommunityResolver {
 
   @Authorized([RIGHTS.COMMUNITIES])
   @Query(() => [Community])
-  async communities(): Promise<Community[]> {
+  communities(): Community[] {
     if (CONFIG.PRODUCTION)
       return [
         new Community({
diff --git a/backend/src/graphql/resolver/ContributionLinkResolver.test.ts b/backend/src/graphql/resolver/ContributionLinkResolver.test.ts
index 62f273829..4563d2a6a 100644
--- a/backend/src/graphql/resolver/ContributionLinkResolver.test.ts
+++ b/backend/src/graphql/resolver/ContributionLinkResolver.test.ts
@@ -1,3 +1,7 @@
+/* eslint-disable @typescript-eslint/no-unsafe-call */
+/* eslint-disable @typescript-eslint/unbound-method */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 
 import Decimal from 'decimal.js-light'
diff --git a/backend/src/graphql/resolver/ContributionLinkResolver.ts b/backend/src/graphql/resolver/ContributionLinkResolver.ts
index 39f202848..cccf47399 100644
--- a/backend/src/graphql/resolver/ContributionLinkResolver.ts
+++ b/backend/src/graphql/resolver/ContributionLinkResolver.ts
@@ -35,7 +35,7 @@ export class ContributionLinkResolver {
       cycle,
       validFrom,
       validTo,
-      maxAmountPerMonth,
+      maxAmountPerMonth = null,
       maxPerCycle,
     }: ContributionLinkArgs,
   ): Promise<ContributionLink> {
@@ -114,7 +114,7 @@ export class ContributionLinkResolver {
       cycle,
       validFrom,
       validTo,
-      maxAmountPerMonth,
+      maxAmountPerMonth = null,
       maxPerCycle,
     }: ContributionLinkArgs,
     @Arg('id', () => Int) id: number,
diff --git a/backend/src/graphql/resolver/ContributionMessageResolver.test.ts b/backend/src/graphql/resolver/ContributionMessageResolver.test.ts
index f3e5e865d..8b5c5a0a7 100644
--- a/backend/src/graphql/resolver/ContributionMessageResolver.test.ts
+++ b/backend/src/graphql/resolver/ContributionMessageResolver.test.ts
@@ -1,3 +1,8 @@
+/* eslint-disable @typescript-eslint/no-unsafe-call */
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/unbound-method */
+/* eslint-disable @typescript-eslint/no-unsafe-return */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 /* eslint-disable @typescript-eslint/explicit-module-boundary-types */
 
@@ -181,7 +186,7 @@ describe('ContributionMessageResolver', () => {
           )
         })
 
-        it('calls sendAddedContributionMessageEmail', async () => {
+        it('calls sendAddedContributionMessageEmail', () => {
           expect(sendAddedContributionMessageEmail).toBeCalledWith({
             firstName: 'Bibi',
             lastName: 'Bloxberg',
diff --git a/backend/src/graphql/resolver/ContributionMessageResolver.ts b/backend/src/graphql/resolver/ContributionMessageResolver.ts
index adfcdf160..c35008ae9 100644
--- a/backend/src/graphql/resolver/ContributionMessageResolver.ts
+++ b/backend/src/graphql/resolver/ContributionMessageResolver.ts
@@ -1,4 +1,5 @@
-import { Arg, Args, Authorized, Ctx, Mutation, Query, Resolver } from 'type-graphql'
+/* eslint-disable @typescript-eslint/restrict-template-expressions */
+import { Arg, Args, Authorized, Ctx, ID, Mutation, Query, Resolver } from 'type-graphql'
 import { getConnection } from '@dbTools/typeorm'
 
 import { ContributionMessage as DbContributionMessage } from '@entity/ContributionMessage'
@@ -68,7 +69,7 @@ export class ContributionMessageResolver {
   @Authorized([RIGHTS.LIST_ALL_CONTRIBUTION_MESSAGES])
   @Query(() => ContributionMessageListResult)
   async listContributionMessages(
-    @Arg('contributionId') contributionId: number,
+    @Arg('contributionId', () => ID) contributionId: number,
     @Args()
     { currentPage = 1, pageSize = 5, order = Order.DESC }: Paginated,
   ): Promise<ContributionMessageListResult> {
diff --git a/backend/src/graphql/resolver/ContributionResolver.test.ts b/backend/src/graphql/resolver/ContributionResolver.test.ts
index 27f6d1c2a..dc31282cb 100644
--- a/backend/src/graphql/resolver/ContributionResolver.test.ts
+++ b/backend/src/graphql/resolver/ContributionResolver.test.ts
@@ -1,3 +1,8 @@
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+/* eslint-disable @typescript-eslint/no-unsafe-call */
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/unbound-method */
+/* eslint-disable @typescript-eslint/no-unsafe-return */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 /* eslint-disable @typescript-eslint/explicit-module-boundary-types */
 
@@ -176,7 +181,7 @@ describe('ContributionResolver', () => {
         })
       })
 
-      afterAll(async () => {
+      afterAll(() => {
         resetToken()
       })
 
@@ -265,7 +270,7 @@ describe('ContributionResolver', () => {
       })
 
       describe('valid input', () => {
-        it('creates contribution', async () => {
+        it('creates contribution', () => {
           expect(pendingContribution.data.createContribution).toMatchObject({
             id: expect.any(Number),
             amount: '100',
@@ -311,7 +316,7 @@ describe('ContributionResolver', () => {
         })
       })
 
-      afterAll(async () => {
+      afterAll(() => {
         resetToken()
       })
 
@@ -452,7 +457,7 @@ describe('ContributionResolver', () => {
               id: pendingContribution.data.createContribution.id,
             })
             contribution.contributionStatus = ContributionStatus.DELETED
-            contribution.save()
+            await contribution.save()
             await mutate({
               mutation: login,
               variables: { email: 'bibi@bloxberg.de', password: 'Aa12345_' },
@@ -464,7 +469,7 @@ describe('ContributionResolver', () => {
               id: pendingContribution.data.createContribution.id,
             })
             contribution.contributionStatus = ContributionStatus.PENDING
-            contribution.save()
+            await contribution.save()
           })
 
           it('throws an error', async () => {
@@ -636,7 +641,7 @@ describe('ContributionResolver', () => {
         })
       })
 
-      afterAll(async () => {
+      afterAll(() => {
         resetToken()
       })
 
@@ -856,7 +861,7 @@ describe('ContributionResolver', () => {
         })
       })
 
-      afterAll(async () => {
+      afterAll(() => {
         resetToken()
       })
 
@@ -1009,7 +1014,7 @@ describe('ContributionResolver', () => {
         })
       })
 
-      afterAll(async () => {
+      afterAll(() => {
         resetToken()
       })
 
@@ -1140,7 +1145,7 @@ describe('ContributionResolver', () => {
         })
       })
 
-      afterAll(async () => {
+      afterAll(() => {
         resetToken()
       })
 
@@ -1720,7 +1725,7 @@ describe('ContributionResolver', () => {
           })
         })
 
-        afterAll(async () => {
+        afterAll(() => {
           resetToken()
         })
 
@@ -1798,7 +1803,7 @@ describe('ContributionResolver', () => {
           })
         })
 
-        afterAll(async () => {
+        afterAll(() => {
           resetToken()
         })
 
@@ -1913,7 +1918,7 @@ describe('ContributionResolver', () => {
           })
 
           describe('valid user to create for', () => {
-            beforeAll(async () => {
+            beforeAll(() => {
               variables.email = 'bibi@bloxberg.de'
               variables.creationDate = 'invalid-date'
             })
@@ -2551,7 +2556,7 @@ describe('ContributionResolver', () => {
               expect(transaction[0].typeId).toEqual(1)
             })
 
-            it('calls sendContributionConfirmedEmail', async () => {
+            it('calls sendContributionConfirmedEmail', () => {
               expect(sendContributionConfirmedEmail).toBeCalledWith({
                 firstName: 'Bibi',
                 lastName: 'Bloxberg',
diff --git a/backend/src/graphql/resolver/ContributionResolver.ts b/backend/src/graphql/resolver/ContributionResolver.ts
index 2469f60ba..8735e9aec 100644
--- a/backend/src/graphql/resolver/ContributionResolver.ts
+++ b/backend/src/graphql/resolver/ContributionResolver.ts
@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/restrict-template-expressions */
 import Decimal from 'decimal.js-light'
 import { Arg, Args, Authorized, Ctx, Int, Mutation, Query, Resolver } from 'type-graphql'
 import { IsNull, getConnection } from '@dbTools/typeorm'
@@ -156,7 +157,7 @@ export class ContributionResolver {
     @Args()
     { currentPage = 1, pageSize = 5, order = Order.DESC }: Paginated,
     @Arg('statusFilter', () => [ContributionStatus], { nullable: true })
-    statusFilter?: ContributionStatus[],
+    statusFilter?: ContributionStatus[] | null,
   ): Promise<ContributionListResult> {
     const [dbContributions, count] = await findContributions(
       order,
@@ -239,14 +240,14 @@ export class ContributionResolver {
     contributionMessage.isModerator = false
     contributionMessage.userId = user.id
     contributionMessage.type = ContributionMessageType.HISTORY
-    ContributionMessage.save(contributionMessage)
+    await ContributionMessage.save(contributionMessage)
 
     contributionToUpdate.amount = amount
     contributionToUpdate.memo = memo
     contributionToUpdate.contributionDate = new Date(creationDate)
     contributionToUpdate.contributionStatus = ContributionStatus.PENDING
     contributionToUpdate.updatedAt = new Date()
-    DbContribution.save(contributionToUpdate)
+    await DbContribution.save(contributionToUpdate)
 
     await EVENT_CONTRIBUTION_UPDATE(user.id, contributionId, amount)
 
@@ -254,7 +255,7 @@ export class ContributionResolver {
   }
 
   @Authorized([RIGHTS.ADMIN_CREATE_CONTRIBUTION])
-  @Mutation(() => [Number])
+  @Mutation(() => [Decimal])
   async adminCreateContribution(
     @Args() { email, amount, memo, creationDate }: AdminCreateContributionArgs,
     @Ctx() context: Context,
@@ -384,7 +385,7 @@ export class ContributionResolver {
     @Args()
     { currentPage = 1, pageSize = 3, order = Order.DESC }: Paginated,
     @Arg('statusFilter', () => [ContributionStatus], { nullable: true })
-    statusFilter?: ContributionStatus[],
+    statusFilter?: ContributionStatus[] | null,
   ): Promise<ContributionListResult> {
     const [dbContributions, count] = await findContributions(
       order,
@@ -433,7 +434,7 @@ export class ContributionResolver {
 
     await EVENT_ADMIN_CONTRIBUTION_DELETE(contribution.userId, contribution.id, contribution.amount)
 
-    sendContributionDeletedEmail({
+    void sendContributionDeletedEmail({
       firstName: user.firstName,
       lastName: user.lastName,
       email: user.emailContact.email,
@@ -527,7 +528,7 @@ export class ContributionResolver {
 
         await queryRunner.commitTransaction()
         logger.info('creation commited successfuly.')
-        sendContributionConfirmedEmail({
+        void sendContributionConfirmedEmail({
           firstName: user.firstName,
           lastName: user.lastName,
           email: user.emailContact.email,
@@ -581,8 +582,8 @@ export class ContributionResolver {
   @Authorized([RIGHTS.OPEN_CREATIONS])
   @Query(() => [OpenCreation])
   async openCreations(
-    @Arg('userId', () => Int, { nullable: true }) userId: number | null,
     @Ctx() context: Context,
+    @Arg('userId', () => Int, { nullable: true }) userId?: number | null,
   ): Promise<OpenCreation[]> {
     const id = userId || getUser(context).id
     const clientTimezoneOffset = getClientTimezoneOffset(context)
@@ -641,7 +642,7 @@ export class ContributionResolver {
       contributionToUpdate.amount,
     )
 
-    sendContributionDeniedEmail({
+    void sendContributionDeniedEmail({
       firstName: user.firstName,
       lastName: user.lastName,
       email: user.emailContact.email,
diff --git a/backend/src/graphql/resolver/EmailOptinCodes.test.ts b/backend/src/graphql/resolver/EmailOptinCodes.test.ts
index 988595723..47fb3963c 100644
--- a/backend/src/graphql/resolver/EmailOptinCodes.test.ts
+++ b/backend/src/graphql/resolver/EmailOptinCodes.test.ts
@@ -1,3 +1,6 @@
+/* eslint-disable @typescript-eslint/no-unsafe-call */
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 /* eslint-disable @typescript-eslint/explicit-module-boundary-types */
 
diff --git a/backend/src/graphql/resolver/GdtResolver.ts b/backend/src/graphql/resolver/GdtResolver.ts
index 1745e7bbd..f440efd3a 100644
--- a/backend/src/graphql/resolver/GdtResolver.ts
+++ b/backend/src/graphql/resolver/GdtResolver.ts
@@ -1,4 +1,7 @@
-import { Resolver, Query, Args, Ctx, Authorized, Arg } from 'type-graphql'
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+/* eslint-disable @typescript-eslint/no-unsafe-return */
+import { Resolver, Query, Args, Ctx, Authorized, Arg, Int } from 'type-graphql'
 
 import { GdtEntryList } from '@model/GdtEntryList'
 import { Order } from '@enum/Order'
@@ -23,6 +26,7 @@ export class GdtResolver {
 
     try {
       const resultGDT = await apiGet(
+        // eslint-disable-next-line @typescript-eslint/restrict-template-expressions
         `${CONFIG.GDT_API_URL}/GdtEntries/listPerEmailApi/${userEntity.emailContact.email}/${currentPage}/${pageSize}/${order}`,
       )
       if (!resultGDT.success) {
@@ -35,7 +39,7 @@ export class GdtResolver {
   }
 
   @Authorized([RIGHTS.GDT_BALANCE])
-  @Query(() => Number)
+  @Query(() => Int, { nullable: true })
   async gdtBalance(@Ctx() context: Context): Promise<number | null> {
     const user = getUser(context)
     try {
@@ -54,9 +58,9 @@ export class GdtResolver {
   }
 
   @Authorized([RIGHTS.EXIST_PID])
-  @Query(() => Number)
+  @Query(() => Int)
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  async existPid(@Arg('pid') pid: number): Promise<number> {
+  async existPid(@Arg('pid', () => Int) pid: number): Promise<number> {
     // load user
     const resultPID = await apiGet(`${CONFIG.GDT_API_URL}/publishers/checkPidApi/${pid}`)
     if (!resultPID.success) {
diff --git a/backend/src/graphql/resolver/KlicktippResolver.ts b/backend/src/graphql/resolver/KlicktippResolver.ts
index 4f88ccdc1..dd137f07c 100644
--- a/backend/src/graphql/resolver/KlicktippResolver.ts
+++ b/backend/src/graphql/resolver/KlicktippResolver.ts
@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/no-unsafe-return */
 import { Resolver, Query, Authorized, Arg, Mutation, Args } from 'type-graphql'
 
 import SubscribeNewsletterArgs from '@arg/SubscribeNewsletterArgs'
diff --git a/backend/src/graphql/resolver/StatisticsResolver.ts b/backend/src/graphql/resolver/StatisticsResolver.ts
index e91840f10..38d0000cb 100644
--- a/backend/src/graphql/resolver/StatisticsResolver.ts
+++ b/backend/src/graphql/resolver/StatisticsResolver.ts
@@ -1,3 +1,5 @@
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+/* eslint-disable @typescript-eslint/no-unsafe-return */
 import Decimal from 'decimal.js-light'
 import { Resolver, Query, Authorized, FieldResolver } from 'type-graphql'
 import { getConnection } from '@dbTools/typeorm'
@@ -15,7 +17,7 @@ import { calculateDecay } from '@/util/decay'
 export class StatisticsResolver {
   @Authorized([RIGHTS.COMMUNITY_STATISTICS])
   @Query(() => CommunityStatistics)
-  async communityStatistics(): Promise<CommunityStatistics> {
+  communityStatistics(): CommunityStatistics {
     return new CommunityStatistics()
   }
 
diff --git a/backend/src/graphql/resolver/TransactionLinkResolver.test.ts b/backend/src/graphql/resolver/TransactionLinkResolver.test.ts
index 60b4551be..fc5ca170a 100644
--- a/backend/src/graphql/resolver/TransactionLinkResolver.test.ts
+++ b/backend/src/graphql/resolver/TransactionLinkResolver.test.ts
@@ -1,3 +1,8 @@
+/* eslint-disable @typescript-eslint/no-unsafe-call */
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+/* eslint-disable @typescript-eslint/restrict-template-expressions */
+/* eslint-disable @typescript-eslint/unbound-method */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 /* eslint-disable @typescript-eslint/explicit-module-boundary-types */
 
@@ -210,7 +215,7 @@ describe('TransactionLinkResolver', () => {
               mutate({
                 mutation: redeemTransactionLink,
                 variables: {
-                  code: 'CL-' + contributionLink.code,
+                  code: `CL-${contributionLink.code}`,
                 },
               }),
             ).resolves.toMatchObject({
@@ -249,7 +254,7 @@ describe('TransactionLinkResolver', () => {
               mutate({
                 mutation: redeemTransactionLink,
                 variables: {
-                  code: 'CL-' + contributionLink.code,
+                  code: `CL-${contributionLink.code}`,
                 },
               }),
             ).resolves.toMatchObject({
@@ -288,7 +293,7 @@ describe('TransactionLinkResolver', () => {
               mutate({
                 mutation: redeemTransactionLink,
                 variables: {
-                  code: 'CL-' + contributionLink.code,
+                  code: `CL-${contributionLink.code}`,
                 },
               }),
             ).resolves.toMatchObject({
diff --git a/backend/src/graphql/resolver/TransactionLinkResolver.ts b/backend/src/graphql/resolver/TransactionLinkResolver.ts
index ab5b52bad..f2d58cb64 100644
--- a/backend/src/graphql/resolver/TransactionLinkResolver.ts
+++ b/backend/src/graphql/resolver/TransactionLinkResolver.ts
@@ -128,7 +128,7 @@ export class TransactionLinkResolver {
   @Authorized([RIGHTS.QUERY_TRANSACTION_LINK])
   @Query(() => QueryLinkResult)
   async queryTransactionLink(@Arg('code') code: string): Promise<typeof QueryLinkResult> {
-    if (code.match(/^CL-/)) {
+    if (/^CL-/.exec(code)) {
       const contributionLink = await DbContributionLink.findOneOrFail(
         { code: code.replace('CL-', '') },
         { withDeleted: true },
@@ -154,7 +154,7 @@ export class TransactionLinkResolver {
     const clientTimezoneOffset = getClientTimezoneOffset(context)
     const user = getUser(context)
 
-    if (code.match(/^CL-/)) {
+    if (/^CL-/.exec(code)) {
       // acquire lock
       const releaseLock = await TRANSACTIONS_LOCK.acquire()
       try {
@@ -341,8 +341,9 @@ export class TransactionLinkResolver {
   async listTransactionLinksAdmin(
     @Args()
     paginated: Paginated,
+    // eslint-disable-next-line type-graphql/wrong-decorator-signature
     @Arg('filters', () => TransactionLinkFilters, { nullable: true })
-    filters: TransactionLinkFilters | null,
+    filters: TransactionLinkFilters | null, // eslint-disable-line type-graphql/invalid-nullable-input-type
     @Arg('userId', () => Int)
     userId: number,
   ): Promise<TransactionLinkResult> {
diff --git a/backend/src/graphql/resolver/TransactionResolver.test.ts b/backend/src/graphql/resolver/TransactionResolver.test.ts
index 6751aa6ad..5f3c71bd3 100644
--- a/backend/src/graphql/resolver/TransactionResolver.test.ts
+++ b/backend/src/graphql/resolver/TransactionResolver.test.ts
@@ -1,3 +1,7 @@
+/* eslint-disable @typescript-eslint/no-unsafe-call */
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+/* eslint-disable @typescript-eslint/unbound-method */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 /* eslint-disable @typescript-eslint/explicit-module-boundary-types */
 
@@ -337,7 +341,7 @@ describe('send coins', () => {
           memo: 'unrepeatable memo',
         })
 
-        expect(EventProtocol.find()).resolves.toContainEqual(
+        await expect(EventProtocol.find()).resolves.toContainEqual(
           expect.objectContaining({
             type: EventProtocolType.TRANSACTION_SEND,
             userId: user[1].id,
@@ -354,7 +358,7 @@ describe('send coins', () => {
           memo: 'unrepeatable memo',
         })
 
-        expect(EventProtocol.find()).resolves.toContainEqual(
+        await expect(EventProtocol.find()).resolves.toContainEqual(
           expect.objectContaining({
             type: EventProtocolType.TRANSACTION_RECEIVE,
             userId: user[0].id,
diff --git a/backend/src/graphql/resolver/TransactionResolver.ts b/backend/src/graphql/resolver/TransactionResolver.ts
index 9d5a1d38c..a11c5b377 100644
--- a/backend/src/graphql/resolver/TransactionResolver.ts
+++ b/backend/src/graphql/resolver/TransactionResolver.ts
@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/restrict-template-expressions */
 /* eslint-disable new-cap */
 /* eslint-disable @typescript-eslint/no-non-null-assertion */
 
@@ -304,7 +305,7 @@ export class TransactionResolver {
   }
 
   @Authorized([RIGHTS.SEND_COINS])
-  @Mutation(() => String)
+  @Mutation(() => Boolean)
   async sendCoins(
     @Args() { email, amount, memo }: TransactionSendArgs,
     @Ctx() context: Context,
diff --git a/backend/src/graphql/resolver/UserResolver.test.ts b/backend/src/graphql/resolver/UserResolver.test.ts
index 19eb04b34..0e613a4aa 100644
--- a/backend/src/graphql/resolver/UserResolver.test.ts
+++ b/backend/src/graphql/resolver/UserResolver.test.ts
@@ -1,3 +1,8 @@
+/* eslint-disable @typescript-eslint/no-unsafe-call */
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+/* eslint-disable @typescript-eslint/no-unsafe-return */
+/* eslint-disable @typescript-eslint/unbound-method */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 /* eslint-disable @typescript-eslint/explicit-module-boundary-types */
 
@@ -182,7 +187,7 @@ describe('UserResolver', () => {
           { email: 'peter@lustig.de' },
           { relations: ['user'] },
         )
-        expect(EventProtocol.find()).resolves.toContainEqual(
+        await expect(EventProtocol.find()).resolves.toContainEqual(
           expect.objectContaining({
             type: EventProtocolType.REGISTER,
             userId: userConatct.user.id,
@@ -210,8 +215,8 @@ describe('UserResolver', () => {
         })
       })
 
-      it('stores the SEND_CONFIRMATION_EMAIL event in the database', () => {
-        expect(EventProtocol.find()).resolves.toContainEqual(
+      it('stores the SEND_CONFIRMATION_EMAIL event in the database', async () => {
+        await expect(EventProtocol.find()).resolves.toContainEqual(
           expect.objectContaining({
             type: EventProtocolType.SEND_CONFIRMATION_EMAIL,
             userId: user[0].id,
@@ -226,7 +231,7 @@ describe('UserResolver', () => {
         mutation = await mutate({ mutation: createUser, variables })
       })
 
-      it('logs an info', async () => {
+      it('logs an info', () => {
         expect(logger.info).toBeCalledWith('User already exists with this email=peter@lustig.de')
       })
 
@@ -239,7 +244,7 @@ describe('UserResolver', () => {
         })
       })
 
-      it('results with partly faked user with random "id"', async () => {
+      it('results with partly faked user with random "id"', () => {
         expect(mutation).toEqual(
           expect.objectContaining({
             data: {
@@ -256,7 +261,7 @@ describe('UserResolver', () => {
           { email: 'peter@lustig.de' },
           { relations: ['user'] },
         )
-        expect(EventProtocol.find()).resolves.toContainEqual(
+        await expect(EventProtocol.find()).resolves.toContainEqual(
           expect.objectContaining({
             type: EventProtocolType.SEND_ACCOUNT_MULTIREGISTRATION_EMAIL,
             userId: userConatct.user.id,
@@ -355,8 +360,8 @@ describe('UserResolver', () => {
           )
         })
 
-        it('stores the ACTIVATE_ACCOUNT event in the database', () => {
-          expect(EventProtocol.find()).resolves.toContainEqual(
+        it('stores the ACTIVATE_ACCOUNT event in the database', async () => {
+          await expect(EventProtocol.find()).resolves.toContainEqual(
             expect.objectContaining({
               type: EventProtocolType.ACTIVATE_ACCOUNT,
               userId: user[0].id,
@@ -364,8 +369,8 @@ describe('UserResolver', () => {
           )
         })
 
-        it('stores the REDEEM_REGISTER event in the database', () => {
-          expect(EventProtocol.find()).resolves.toContainEqual(
+        it('stores the REDEEM_REGISTER event in the database', async () => {
+          await expect(EventProtocol.find()).resolves.toContainEqual(
             expect.objectContaining({
               type: EventProtocolType.REDEEM_REGISTER,
               userId: result.data.createUser.id,
@@ -680,7 +685,7 @@ describe('UserResolver', () => {
           { email: 'bibi@bloxberg.de' },
           { relations: ['user'] },
         )
-        expect(EventProtocol.find()).resolves.toContainEqual(
+        await expect(EventProtocol.find()).resolves.toContainEqual(
           expect.objectContaining({
             type: EventProtocolType.LOGIN,
             userId: userConatct.user.id,
@@ -927,8 +932,8 @@ describe('UserResolver', () => {
           )
         })
 
-        it('stores the LOGIN event in the database', () => {
-          expect(EventProtocol.find()).resolves.toContainEqual(
+        it('stores the LOGIN event in the database', async () => {
+          await expect(EventProtocol.find()).resolves.toContainEqual(
             expect.objectContaining({
               type: EventProtocolType.LOGIN,
               userId: user[0].id,
@@ -1847,7 +1852,7 @@ describe('UserResolver', () => {
               { email: 'bibi@bloxberg.de' },
               { relations: ['user'] },
             )
-            expect(EventProtocol.find()).resolves.toContainEqual(
+            await expect(EventProtocol.find()).resolves.toContainEqual(
               expect.objectContaining({
                 type: EventProtocolType.ADMIN_SEND_CONFIRMATION_EMAIL,
                 userId: userConatct.user.id,
diff --git a/backend/src/graphql/resolver/UserResolver.ts b/backend/src/graphql/resolver/UserResolver.ts
index f9617b0df..ad357116a 100644
--- a/backend/src/graphql/resolver/UserResolver.ts
+++ b/backend/src/graphql/resolver/UserResolver.ts
@@ -1,3 +1,7 @@
+/* eslint-disable @typescript-eslint/no-unsafe-call */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/restrict-template-expressions */
 import i18n from 'i18n'
 import { v4 as uuidv4 } from 'uuid'
 import {
@@ -166,11 +170,11 @@ export class UserResolver {
 
     // Elopage Status & Stored PublisherId
     user.hasElopage = await this.hasElopage({ ...context, user: dbUser })
-    logger.info('user.hasElopage=' + user.hasElopage)
+    logger.info('user.hasElopage', user.hasElopage)
     if (!user.hasElopage && publisherId) {
       user.publisherId = publisherId
       dbUser.publisherId = publisherId
-      DbUser.save(dbUser)
+      await DbUser.save(dbUser)
     }
 
     context.setHeaders.push({
@@ -184,8 +188,8 @@ export class UserResolver {
   }
 
   @Authorized([RIGHTS.LOGOUT])
-  @Mutation(() => String)
-  async logout(): Promise<boolean> {
+  @Mutation(() => Boolean)
+  logout(): boolean {
     // TODO: Event still missing here!!
     // TODO: We dont need this anymore, but might need this in the future in oder to invalidate a valid JWT-Token.
     // Furthermore this hook can be useful for tracking user behaviour (did he logout or not? Warn him if he didn't on next login)
@@ -202,7 +206,7 @@ export class UserResolver {
   @Mutation(() => User)
   async createUser(
     @Args()
-    { email, firstName, lastName, language, publisherId, redeemCode = null }: CreateUserArgs,
+    { email, firstName, lastName, language, publisherId = null, redeemCode = null }: CreateUserArgs,
   ): Promise<User> {
     logger.addContext('user', 'unknown')
     logger.info(
@@ -239,7 +243,7 @@ export class UserResolver {
         user.lastName = lastName
         user.language = language
         user.publisherId = publisherId
-        logger.debug('partly faked user=' + user)
+        logger.debug('partly faked user', user)
 
         const emailSent = await sendAccountMultiRegistrationEmail({
           firstName: foundUser.firstName, // this is the real name of the email owner, but just "firstName" would be the name of the new registrant which shall not be passed to the outside
@@ -272,22 +276,22 @@ export class UserResolver {
     dbUser.firstName = firstName
     dbUser.lastName = lastName
     dbUser.language = language
-    dbUser.publisherId = publisherId
+    dbUser.publisherId = publisherId || 0
     dbUser.passwordEncryptionType = PasswordEncryptionType.NO_PASSWORD
-    logger.debug('new dbUser=' + dbUser)
+    logger.debug('new dbUser', dbUser)
     if (redeemCode) {
-      if (redeemCode.match(/^CL-/)) {
+      if (/^CL-/.exec(redeemCode)) {
         const contributionLink = await DbContributionLink.findOne({
           code: redeemCode.replace('CL-', ''),
         })
-        logger.info('redeemCode found contributionLink=' + contributionLink)
+        logger.info('redeemCode found contributionLink', contributionLink)
         if (contributionLink) {
           dbUser.contributionLinkId = contributionLink.id
           eventRegisterRedeem.contributionId = contributionLink.id
         }
       } else {
         const transactionLink = await DbTransactionLink.findOne({ code: redeemCode })
-        logger.info('redeemCode found transactionLink=' + transactionLink)
+        logger.info('redeemCode found transactionLink', transactionLink)
         if (transactionLink) {
           dbUser.referrerId = transactionLink.userId
           eventRegisterRedeem.transactionId = transactionLink.id
@@ -654,7 +658,7 @@ export class UserResolver {
         return 'user.' + fieldName
       }),
       searchText,
-      filters,
+      filters || null,
       currentPage,
       pageSize,
     )
diff --git a/backend/src/graphql/resolver/semaphore.test.ts b/backend/src/graphql/resolver/semaphore.test.ts
index e334910f1..70e3e5f96 100644
--- a/backend/src/graphql/resolver/semaphore.test.ts
+++ b/backend/src/graphql/resolver/semaphore.test.ts
@@ -1,3 +1,7 @@
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+/* eslint-disable @typescript-eslint/no-unsafe-call */
+/* eslint-disable @typescript-eslint/restrict-template-expressions */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 
 import Decimal from 'decimal.js-light'
@@ -79,7 +83,7 @@ describe('semaphore', () => {
         maxPerCycle: 1,
       },
     })
-    contributionLinkCode = 'CL-' + contributionLink.code
+    contributionLinkCode = `CL-${contributionLink.code}`
     await mutate({
       mutation: login,
       variables: { email: 'bob@baumeister.de', password: 'Aa12345_' },
diff --git a/backend/src/graphql/resolver/util/creations.test.ts b/backend/src/graphql/resolver/util/creations.test.ts
index 4d8132333..4eabec500 100644
--- a/backend/src/graphql/resolver/util/creations.test.ts
+++ b/backend/src/graphql/resolver/util/creations.test.ts
@@ -1,3 +1,6 @@
+/* eslint-disable @typescript-eslint/no-unsafe-call */
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 /* eslint-disable @typescript-eslint/explicit-module-boundary-types */
 
diff --git a/backend/src/graphql/resolver/util/creations.ts b/backend/src/graphql/resolver/util/creations.ts
index b9ba2e69f..33b48a3a3 100644
--- a/backend/src/graphql/resolver/util/creations.ts
+++ b/backend/src/graphql/resolver/util/creations.ts
@@ -1,3 +1,5 @@
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
 import LogError from '@/server/LogError'
 import { backendLogger as logger } from '@/server/logger'
 import { getConnection } from '@dbTools/typeorm'
diff --git a/backend/src/index.ts b/backend/src/index.ts
index 10b7c91ac..cd6d002cc 100644
--- a/backend/src/index.ts
+++ b/backend/src/index.ts
@@ -17,7 +17,7 @@ async function main() {
       console.log(`GraphIQL available at http://localhost:${CONFIG.PORT}`)
     }
   })
-  startValidateCommunities(Number(CONFIG.FEDERATION_VALIDATE_COMMUNITY_TIMER))
+  void startValidateCommunities(Number(CONFIG.FEDERATION_VALIDATE_COMMUNITY_TIMER))
 }
 
 main().catch((e) => {
diff --git a/backend/src/middleware/klicktippMiddleware.ts b/backend/src/middleware/klicktippMiddleware.ts
index 6bdaa63fd..0469b4ccc 100644
--- a/backend/src/middleware/klicktippMiddleware.ts
+++ b/backend/src/middleware/klicktippMiddleware.ts
@@ -1,3 +1,7 @@
+/* eslint-disable @typescript-eslint/no-unsafe-return */
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+/* eslint-disable @typescript-eslint/restrict-template-expressions */
 import { MiddlewareFn } from 'type-graphql'
 import { /* klicktippSignIn, */ getKlickTippUser } from '@/apis/KlicktippController'
 import { KlickTipp } from '@model/KlickTipp'
diff --git a/backend/src/password/EncryptorUtils.ts b/backend/src/password/EncryptorUtils.ts
index d03f5d169..93e519fe4 100644
--- a/backend/src/password/EncryptorUtils.ts
+++ b/backend/src/password/EncryptorUtils.ts
@@ -1,3 +1,6 @@
+/* eslint-disable @typescript-eslint/no-unsafe-call */
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
 import CONFIG from '@/config'
 import LogError from '@/server/LogError'
 import { backendLogger as logger } from '@/server/logger'
@@ -9,7 +12,7 @@ const sodium = require('sodium-native')
 
 // We will reuse this for changePassword
 export const isValidPassword = (password: string): boolean => {
-  return !!password.match(/^(?=.*[a-z])(?=.*[A-Z])(?=.*[0-9])(?=.*[^a-zA-Z0-9 \\t\\n\\r]).{8,}$/)
+  return !!/^(?=.*[a-z])(?=.*[A-Z])(?=.*[0-9])(?=.*[^a-zA-Z0-9 \\t\\n\\r]).{8,}$/.exec(password)
 }
 
 export const SecretKeyCryptographyCreateKey = (salt: string, password: string): Buffer[] => {
diff --git a/backend/src/seeds/factory/contributionLink.ts b/backend/src/seeds/factory/contributionLink.ts
index 08f784604..5925cdcfe 100644
--- a/backend/src/seeds/factory/contributionLink.ts
+++ b/backend/src/seeds/factory/contributionLink.ts
@@ -1,3 +1,6 @@
+/* eslint-disable @typescript-eslint/no-unsafe-return */
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/unbound-method */
 import { ApolloServerTestClient } from 'apollo-server-testing'
 import { login, createContributionLink } from '@/seeds/graphql/mutations'
 import { ContributionLink } from '@model/ContributionLink'
diff --git a/backend/src/seeds/factory/creation.ts b/backend/src/seeds/factory/creation.ts
index 69d77aa03..db58c9d51 100644
--- a/backend/src/seeds/factory/creation.ts
+++ b/backend/src/seeds/factory/creation.ts
@@ -1,3 +1,7 @@
+/* eslint-disable @typescript-eslint/no-unsafe-return */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/unbound-method */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 /* eslint-disable @typescript-eslint/explicit-module-boundary-types */
 
diff --git a/backend/src/seeds/factory/transactionLink.ts b/backend/src/seeds/factory/transactionLink.ts
index be5a01d22..797a93183 100644
--- a/backend/src/seeds/factory/transactionLink.ts
+++ b/backend/src/seeds/factory/transactionLink.ts
@@ -1,3 +1,5 @@
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+/* eslint-disable @typescript-eslint/unbound-method */
 import { ApolloServerTestClient } from 'apollo-server-testing'
 import { login, createTransactionLink } from '@/seeds/graphql/mutations'
 import { TransactionLinkInterface } from '@/seeds/transactionLink/TransactionLinkInterface'
diff --git a/backend/src/seeds/factory/user.ts b/backend/src/seeds/factory/user.ts
index d566275db..854e5a4ed 100644
--- a/backend/src/seeds/factory/user.ts
+++ b/backend/src/seeds/factory/user.ts
@@ -1,3 +1,5 @@
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+/* eslint-disable @typescript-eslint/unbound-method */
 import { createUser, setPassword } from '@/seeds/graphql/mutations'
 import { User } from '@entity/User'
 import { UserInterface } from '@/seeds/users/UserInterface'
diff --git a/backend/src/seeds/index.ts b/backend/src/seeds/index.ts
index 9e1939db8..55cd65ec1 100644
--- a/backend/src/seeds/index.ts
+++ b/backend/src/seeds/index.ts
@@ -1,3 +1,7 @@
+/* eslint-disable @typescript-eslint/no-unsafe-return */
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+/* eslint-disable @typescript-eslint/no-unsafe-call */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 /* eslint-disable @typescript-eslint/explicit-module-boundary-types */
 
@@ -94,4 +98,4 @@ const run = async () => {
   await con.close()
 }
 
-run()
+void run()
diff --git a/backend/src/server/LogError.test.ts b/backend/src/server/LogError.test.ts
index 6654c42f3..5aa1cae21 100644
--- a/backend/src/server/LogError.test.ts
+++ b/backend/src/server/LogError.test.ts
@@ -1,3 +1,5 @@
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/unbound-method */
 import { logger } from '@test/testSetup'
 
 import LogError from './LogError'
diff --git a/backend/src/server/createServer.ts b/backend/src/server/createServer.ts
index 390ff1c6b..0c5009b6f 100644
--- a/backend/src/server/createServer.ts
+++ b/backend/src/server/createServer.ts
@@ -1,3 +1,6 @@
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+/* eslint-disable @typescript-eslint/restrict-template-expressions */
+/* eslint-disable @typescript-eslint/unbound-method */
 import 'reflect-metadata'
 
 import { ApolloServer } from 'apollo-server-express'
@@ -71,6 +74,7 @@ const createServer = async (
   app.use(localization.init)
 
   // Elopage Webhook
+  // eslint-disable-next-line @typescript-eslint/no-misused-promises
   app.post('/hook/elopage/' + CONFIG.WEBHOOK_ELOPAGE_SECRET, elopageWebhook)
 
   // Apollo Server
diff --git a/backend/src/server/logger.ts b/backend/src/server/logger.ts
index 0cfa5689b..5cfa94285 100644
--- a/backend/src/server/logger.ts
+++ b/backend/src/server/logger.ts
@@ -1,3 +1,5 @@
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
 import log4js from 'log4js'
 import CONFIG from '@/config'
 
diff --git a/backend/src/server/plugins.ts b/backend/src/server/plugins.ts
index 7ecbedf2a..bc2495b71 100644
--- a/backend/src/server/plugins.ts
+++ b/backend/src/server/plugins.ts
@@ -1,3 +1,8 @@
+/* eslint-disable @typescript-eslint/no-unsafe-call */
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+/* eslint-disable @typescript-eslint/restrict-template-expressions */
+/* eslint-disable @typescript-eslint/no-unsafe-return */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 /* eslint-disable @typescript-eslint/explicit-module-boundary-types */
 
diff --git a/backend/src/typeorm/repository/TransactionLink.ts b/backend/src/typeorm/repository/TransactionLink.ts
index 46926673a..7df1fd465 100644
--- a/backend/src/typeorm/repository/TransactionLink.ts
+++ b/backend/src/typeorm/repository/TransactionLink.ts
@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
 import { Repository, EntityRepository } from '@dbTools/typeorm'
 import { TransactionLink as dbTransactionLink } from '@entity/TransactionLink'
 import Decimal from 'decimal.js-light'
diff --git a/backend/src/typeorm/repository/User.ts b/backend/src/typeorm/repository/User.ts
index 4972aa9c4..e72a6e717 100644
--- a/backend/src/typeorm/repository/User.ts
+++ b/backend/src/typeorm/repository/User.ts
@@ -7,7 +7,7 @@ export class UserRepository extends Repository<DbUser> {
   async findBySearchCriteriaPagedFiltered(
     select: string[],
     searchCriteria: string,
-    filters: SearchUsersFilters,
+    filters: SearchUsersFilters | null,
     currentPage: number,
     pageSize: number,
   ): Promise<[DbUser[], number]> {
diff --git a/backend/src/util/decay.test.ts b/backend/src/util/decay.test.ts
index f1111fab4..cf00ec851 100644
--- a/backend/src/util/decay.test.ts
+++ b/backend/src/util/decay.test.ts
@@ -10,13 +10,13 @@ describe('utils/decay', () => {
       // TODO: toString() was required, we could not compare two decimals
       expect(decayFormula(amount, seconds).toString()).toBe('0.999999978035040489732012')
     })
-    it('has correct backward calculation', async () => {
+    it('has correct backward calculation', () => {
       const amount = new Decimal(1.0)
       const seconds = -1
       expect(decayFormula(amount, seconds).toString()).toBe('1.000000021964959992727444')
     })
     // we get pretty close, but not exact here, skipping
-    it.skip('has correct forward calculation', async () => {
+    it.skip('has correct forward calculation', () => {
       const amount = new Decimal(1.0).div(
         new Decimal('0.99999997803504048973201202316767079413460520837376'),
       )
@@ -24,7 +24,7 @@ describe('utils/decay', () => {
       expect(decayFormula(amount, seconds).toString()).toBe('1.0')
     })
   })
-  it('has base 0.99999997802044727', async () => {
+  it('has base 0.99999997802044727', () => {
     const now = new Date()
     now.setSeconds(1)
     const oneSecondAgo = new Date(now.getTime())
@@ -34,7 +34,7 @@ describe('utils/decay', () => {
     )
   })
 
-  it('returns input amount when from and to is the same', async () => {
+  it('returns input amount when from and to is the same', () => {
     const now = new Date()
     expect(calculateDecay(new Decimal(100.0), now, now).balance.toString()).toBe('100')
   })
diff --git a/backend/src/util/klicktipp.ts b/backend/src/util/klicktipp.ts
index 02bdd853b..baa7970fc 100644
--- a/backend/src/util/klicktipp.ts
+++ b/backend/src/util/klicktipp.ts
@@ -26,4 +26,4 @@ export async function retrieveNotRegisteredEmails(): Promise<string[]> {
   return notRegisteredUser
 }
 
-retrieveNotRegisteredEmails()
+void retrieveNotRegisteredEmails()
diff --git a/backend/src/webhook/elopage.ts b/backend/src/webhook/elopage.ts
index 87af4088c..e3e1bbecb 100644
--- a/backend/src/webhook/elopage.ts
+++ b/backend/src/webhook/elopage.ts
@@ -1,3 +1,7 @@
+/* eslint-disable @typescript-eslint/no-unsafe-call */
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+/* eslint-disable @typescript-eslint/restrict-template-expressions */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 /* eslint-disable @typescript-eslint/explicit-module-boundary-types */
 /*
@@ -115,7 +119,7 @@ export const elopageWebhook = async (req: any, res: any): Promise<void> => {
     // Validate inputs
     if (
       email === '' ||
-      !email.match(VALIDATE_EMAIL) ||
+      !VALIDATE_EMAIL.exec(email) ||
       firstName === '' ||
       firstName.match(VALIDATE_NAME) ||
       lastName === '' ||
diff --git a/backend/test/extensions.ts b/backend/test/extensions.ts
index 69c2ff7a6..26fb11510 100644
--- a/backend/test/extensions.ts
+++ b/backend/test/extensions.ts
@@ -1,3 +1,6 @@
+/* eslint-disable @typescript-eslint/no-unsafe-call */
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/restrict-template-expressions */
 /* eslint-disable @typescript-eslint/no-empty-interface */
 
 import Decimal from 'decimal.js-light'
diff --git a/backend/test/helpers.ts b/backend/test/helpers.ts
index 1935b01a0..a5f721717 100644
--- a/backend/test/helpers.ts
+++ b/backend/test/helpers.ts
@@ -1,3 +1,8 @@
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+/* eslint-disable @typescript-eslint/no-unsafe-return */
+/* eslint-disable @typescript-eslint/no-unsafe-call */
+/* eslint-disable @typescript-eslint/no-unsafe-member-access */
+/* eslint-disable @typescript-eslint/unbound-method */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 /* eslint-disable @typescript-eslint/explicit-module-boundary-types */
 
diff --git a/backend/test/testSetup.ts b/backend/test/testSetup.ts
index 300a9cbf3..b13e3cf26 100644
--- a/backend/test/testSetup.ts
+++ b/backend/test/testSetup.ts
@@ -1,3 +1,5 @@
+/* eslint-disable @typescript-eslint/no-unsafe-assignment */
+/* eslint-disable @typescript-eslint/no-unsafe-return */
 import CONFIG from '@/config'
 import { backendLogger as logger } from '@/server/logger'
 import { i18n } from '@/server/localization'