diff --git a/backend/.eslintrc.cjs b/backend/.eslintrc.cjs
index 684c26948..51adb6831 100644
--- a/backend/.eslintrc.cjs
+++ b/backend/.eslintrc.cjs
@@ -181,7 +181,7 @@ module.exports = {
       extends: [
         'plugin:@typescript-eslint/recommended',
         'plugin:@typescript-eslint/recommended-requiring-type-checking',
-        // 'plugin:@typescript-eslint/strict',
+        'plugin:@typescript-eslint/strict',
         'prettier',
       ],
       rules: {
diff --git a/backend/src/middleware/notifications/notificationsMiddleware.ts b/backend/src/middleware/notifications/notificationsMiddleware.ts
index 5d2febffd..f7be031c8 100644
--- a/backend/src/middleware/notifications/notificationsMiddleware.ts
+++ b/backend/src/middleware/notifications/notificationsMiddleware.ts
@@ -19,7 +19,7 @@ import { pubsub, NOTIFICATION_ADDED, ROOM_COUNT_UPDATED, CHAT_MESSAGE_ADDED } fr
 import extractMentionedUsers from './mentions/extractMentionedUsers'
 
 const queryNotificationEmails = async (context, notificationUserIds) => {
-  if (!(notificationUserIds && notificationUserIds.length)) return []
+  if (!notificationUserIds?.length) return []
   const userEmailCypher = `
     MATCH (user: User)
     // blocked users are filtered out from notifications already
@@ -360,7 +360,7 @@ const notifyMemberOfGroup = async (groupId, userId, reason, context) => {
 }
 
 const notifyUsersOfMention = async (label, id, idsOfUsers, reason, context) => {
-  if (!(idsOfUsers && idsOfUsers.length)) return []
+  if (!idsOfUsers?.length) return []
   await validateNotifyUsers(label, reason)
   let mentionedCypher
   switch (reason) {
diff --git a/backend/src/middleware/permissionsMiddleware.ts b/backend/src/middleware/permissionsMiddleware.ts
index a17072c4b..20063de11 100644
--- a/backend/src/middleware/permissionsMiddleware.ts
+++ b/backend/src/middleware/permissionsMiddleware.ts
@@ -18,7 +18,7 @@ const neode = getNeode()
 const isAuthenticated = rule({
   cache: 'contextual',
 })(async (_parent, _args, ctx, _info) => {
-  return !!(ctx && ctx.user && ctx.user.id)
+  return !!ctx?.user?.id
 })
 
 const isModerator = rule()(async (_parent, _args, { user }, _info) => {
@@ -62,7 +62,7 @@ const isMySocialMedia = rule({
 const isAllowedToChangeGroupSettings = rule({
   cache: 'no_cache',
 })(async (_parent, args, { user, driver }) => {
-  if (!(user && user.id)) return false
+  if (!user?.id) return false
   const ownerId = user.id
   const { id: groupId } = args
   const session = driver.session()
@@ -92,7 +92,7 @@ const isAllowedToChangeGroupSettings = rule({
 const isAllowedSeeingGroupMembers = rule({
   cache: 'no_cache',
 })(async (_parent, args, { user, driver }) => {
-  if (!(user && user.id)) return false
+  if (!user?.id) return false
   const { id: groupId } = args
   const session = driver.session()
   const readTxPromise = session.readTransaction(async (transaction) => {
@@ -128,7 +128,7 @@ const isAllowedSeeingGroupMembers = rule({
 const isAllowedToChangeGroupMemberRole = rule({
   cache: 'no_cache',
 })(async (_parent, args, { user, driver }) => {
-  if (!(user && user.id)) return false
+  if (!user?.id) return false
   const currentUserId = user.id
   const { groupId, userId, roleInGroup } = args
   if (currentUserId === userId) return false
@@ -175,7 +175,7 @@ const isAllowedToChangeGroupMemberRole = rule({
 const isAllowedToJoinGroup = rule({
   cache: 'no_cache',
 })(async (_parent, args, { user, driver }) => {
-  if (!(user && user.id)) return false
+  if (!user?.id) return false
   const { groupId, userId } = args
   const session = driver.session()
   const readTxPromise = session.readTransaction(async (transaction) => {
@@ -205,7 +205,7 @@ const isAllowedToJoinGroup = rule({
 const isAllowedToLeaveGroup = rule({
   cache: 'no_cache',
 })(async (_parent, args, { user, driver }) => {
-  if (!(user && user.id)) return false
+  if (!user?.id) return false
   const { groupId, userId } = args
   if (user.id !== userId) return false
   const session = driver.session()
@@ -235,7 +235,7 @@ const isAllowedToLeaveGroup = rule({
 const isMemberOfGroup = rule({
   cache: 'no_cache',
 })(async (_parent, args, { user, driver }) => {
-  if (!(user && user.id)) return false
+  if (!user?.id) return false
   const { groupId } = args
   if (!groupId) return true
   const userId = user.id
@@ -263,7 +263,7 @@ const isMemberOfGroup = rule({
 const canRemoveUserFromGroup = rule({
   cache: 'no_cache',
 })(async (_parent, args, { user, driver }) => {
-  if (!(user && user.id)) return false
+  if (!user?.id) return false
   const { groupId, userId } = args
   const currentUserId = user.id
   if (currentUserId === userId) return false
@@ -299,7 +299,7 @@ const canRemoveUserFromGroup = rule({
 const canCommentPost = rule({
   cache: 'no_cache',
 })(async (_parent, args, { user, driver }) => {
-  if (!(user && user.id)) return false
+  if (!user?.id) return false
   const { postId } = args
   const userId = user.id
   const session = driver.session()
diff --git a/backend/src/middleware/sentryMiddleware.ts b/backend/src/middleware/sentryMiddleware.ts
index 6577be4ee..743ec32df 100644
--- a/backend/src/middleware/sentryMiddleware.ts
+++ b/backend/src/middleware/sentryMiddleware.ts
@@ -21,7 +21,7 @@ if (CONFIG.SENTRY_DSN_BACKEND) {
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
     withScope: (scope, error, context: any) => {
       scope.setUser({
-        id: context.user && context.user.id,
+        id: context.user?.id,
       })
       scope.setExtra('body', context.req.body)
       scope.setExtra('origin', context.req.headers.origin)
diff --git a/backend/src/middleware/validation/validationMiddleware.ts b/backend/src/middleware/validation/validationMiddleware.ts
index 317595ee3..75f8f5d09 100644
--- a/backend/src/middleware/validation/validationMiddleware.ts
+++ b/backend/src/middleware/validation/validationMiddleware.ts
@@ -87,7 +87,7 @@ const validateReview = async (resolve, root, args, context, info) => {
   try {
     const txResult = await reportReadTxPromise
     existingReportedResource = txResult
-    if (!existingReportedResource || !existingReportedResource.length)
+    if (!existingReportedResource?.length)
       throw new Error(`Resource not found or is not a Post|Comment|User!`)
     existingReportedResource = existingReportedResource[0]
     if (!existingReportedResource.filed)
diff --git a/backend/src/schema/resolvers/emails.ts b/backend/src/schema/resolvers/emails.ts
index d4313558e..be721dda5 100644
--- a/backend/src/schema/resolvers/emails.ts
+++ b/backend/src/schema/resolvers/emails.ts
@@ -48,7 +48,7 @@ export default {
 
       // check email does not belong to anybody
       const existingEmail = await existingEmailAddress({ args, context })
-      if (existingEmail && existingEmail.alreadyExistingEmail && existingEmail.user)
+      if (existingEmail?.alreadyExistingEmail && existingEmail.user)
         return existingEmail.alreadyExistingEmail
 
       const nonce = generateNonce()
diff --git a/backend/src/schema/resolvers/groups.spec.ts b/backend/src/schema/resolvers/groups.spec.ts
index a61d7e8b9..c8ce48c37 100644
--- a/backend/src/schema/resolvers/groups.spec.ts
+++ b/backend/src/schema/resolvers/groups.spec.ts
@@ -2429,7 +2429,7 @@ describe('in mode', () => {
                   id: groupId,
                 },
               })
-              return result.data && result.data.GroupMembers
+              return result.data?.GroupMembers
                 ? !!result.data.GroupMembers.find((member) => member.id === userId)
                 : null
             }
diff --git a/backend/src/schema/resolvers/helpers/Resolver.ts b/backend/src/schema/resolvers/helpers/Resolver.ts
index cad886ace..2d7faa7b7 100644
--- a/backend/src/schema/resolvers/helpers/Resolver.ts
+++ b/backend/src/schema/resolvers/helpers/Resolver.ts
@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/no-dynamic-delete */
 /* eslint-disable @typescript-eslint/require-await */
 /* eslint-disable @typescript-eslint/no-unsafe-argument */
 /* eslint-disable @typescript-eslint/restrict-template-expressions */
diff --git a/backend/src/schema/resolvers/helpers/events.ts b/backend/src/schema/resolvers/helpers/events.ts
index ba68fb587..3e5f8d5a8 100644
--- a/backend/src/schema/resolvers/helpers/events.ts
+++ b/backend/src/schema/resolvers/helpers/events.ts
@@ -22,7 +22,7 @@ export const validateEventParams = (params) => {
       throw new UserInputError('Event venue must be present if event location is given!')
     }
     params.eventVenue = eventInput.eventVenue
-    params.eventLocationName = eventInput.eventLocationName && eventInput.eventLocationName.trim()
+    params.eventLocationName = eventInput.eventLocationName?.trim()
     if (params.eventLocationName) {
       locationName = params.eventLocationName
     } else {
diff --git a/backend/src/schema/resolvers/helpers/filterInvisiblePosts.ts b/backend/src/schema/resolvers/helpers/filterInvisiblePosts.ts
index 7769ac5f9..2a264ced4 100644
--- a/backend/src/schema/resolvers/helpers/filterInvisiblePosts.ts
+++ b/backend/src/schema/resolvers/helpers/filterInvisiblePosts.ts
@@ -9,7 +9,7 @@ const getInvisiblePosts = async (context) => {
   const readTxResultPromise = await session.readTransaction(async (transaction) => {
     let cypher = ''
     const { user } = context
-    if (user && user.id) {
+    if (user?.id) {
       cypher = `
         MATCH (post:Post)<-[:CANNOT_SEE]-(user:User { id: $userId })
         RETURN collect(post.id) AS invisiblePostIds`
diff --git a/backend/src/schema/resolvers/helpers/filterPostsOfMyGroups.ts b/backend/src/schema/resolvers/helpers/filterPostsOfMyGroups.ts
index 255d32c04..9d40b097e 100644
--- a/backend/src/schema/resolvers/helpers/filterPostsOfMyGroups.ts
+++ b/backend/src/schema/resolvers/helpers/filterPostsOfMyGroups.ts
@@ -6,7 +6,7 @@ import { mergeWith, isArray } from 'lodash'
 
 const getMyGroupIds = async (context) => {
   const { user } = context
-  if (!(user && user.id)) return []
+  if (!user?.id) return []
   const session = context.driver.session()
 
   const readTxResultPromise = await session.readTransaction(async (transaction) => {
@@ -26,7 +26,7 @@ const getMyGroupIds = async (context) => {
 }
 
 export const filterPostsOfMyGroups = async (params, context) => {
-  if (!(params.filter && params.filter.postsInMyGroups)) return params
+  if (!params.filter?.postsInMyGroups) return params
   delete params.filter.postsInMyGroups
   const myGroupIds = await getMyGroupIds(context)
   params.filter = mergeWith(
diff --git a/backend/src/schema/resolvers/passwordReset.ts b/backend/src/schema/resolvers/passwordReset.ts
index 9995db969..ab53d65fa 100644
--- a/backend/src/schema/resolvers/passwordReset.ts
+++ b/backend/src/schema/resolvers/passwordReset.ts
@@ -47,7 +47,7 @@ export default {
           )
         })
         const [reset] = await passwordResetTxPromise
-        return !!(reset && reset.properties.usedAt)
+        return !!reset?.properties.usedAt
       } finally {
         session.close()
       }
diff --git a/backend/src/schema/resolvers/user_management.ts b/backend/src/schema/resolvers/user_management.ts
index 77f26ceb4..13437e815 100644
--- a/backend/src/schema/resolvers/user_management.ts
+++ b/backend/src/schema/resolvers/user_management.ts
@@ -49,7 +49,7 @@ export default {
         ) {
           delete currentUser.encryptedPassword
           return encode(currentUser)
-        } else if (currentUser && currentUser.disabled) {
+        } else if (currentUser?.disabled) {
           throw new AuthenticationError('Your account has been disabled.')
         } else {
           throw new AuthenticationError('Incorrect email address or password.')
diff --git a/backend/src/schema/resolvers/users.ts b/backend/src/schema/resolvers/users.ts
index 0abee49fd..4f1fb6d5b 100644
--- a/backend/src/schema/resolvers/users.ts
+++ b/backend/src/schema/resolvers/users.ts
@@ -228,7 +228,7 @@ export default {
       const session = context.driver.session()
 
       const deleteUserTxResultPromise = session.writeTransaction(async (transaction) => {
-        if (resource && resource.length) {
+        if (resource?.length) {
           await Promise.all(
             resource.map(async (node) => {
               const txResult = await transaction.run(
diff --git a/backend/src/schema/resolvers/users/location.ts b/backend/src/schema/resolvers/users/location.ts
index 2a4ce6427..d32c03cd2 100644
--- a/backend/src/schema/resolvers/users/location.ts
+++ b/backend/src/schema/resolvers/users/location.ts
@@ -47,8 +47,8 @@ const createLocation = async (session, mapboxData) => {
     nameRU: mapboxData.text_ru,
     type: mapboxData.id.split('.')[0].toLowerCase(),
     address: mapboxData.address,
-    lng: mapboxData.center && mapboxData.center.length ? mapboxData.center[0] : null,
-    lat: mapboxData.center && mapboxData.center.length ? mapboxData.center[1] : null,
+    lng: mapboxData.center?.length ? mapboxData.center[0] : null,
+    lat: mapboxData.center?.length ? mapboxData.center[1] : null,
   }
 
   let mutation =
@@ -95,7 +95,7 @@ export const createOrUpdateLocations = async (nodeLabel, nodeId, locationName, s
 
     debug(res)
 
-    if (!res || !res.features || !res.features[0]) {
+    if (!res?.features?.[0]) {
       throw new UserInputError('locationName is invalid')
     }
 
@@ -110,7 +110,7 @@ export const createOrUpdateLocations = async (nodeLabel, nodeId, locationName, s
       data = res.features[0]
     }
 
-    if (!data || !data.place_type || !data.place_type.length) {
+    if (!data?.place_type?.length) {
       throw new UserInputError('locationName is invalid')
     }
 
@@ -172,7 +172,7 @@ export const queryLocations = async ({ place, lang }) => {
     `https://api.mapbox.com/geocoding/v5/mapbox.places/${place}.json?access_token=${CONFIG.MAPBOX_TOKEN}&types=region,place,country&language=${lang}`,
   )
   // Return empty array if no location found or error occurred
-  if (!res || !res.features) {
+  if (!res?.features) {
     return []
   }
   return res.features