diff --git a/packages/hoppscotch-backend/prisma/schema.prisma b/packages/hoppscotch-backend/prisma/schema.prisma
index f899da36..28e11e01 100644
--- a/packages/hoppscotch-backend/prisma/schema.prisma
+++ b/packages/hoppscotch-backend/prisma/schema.prisma
@@ -79,14 +79,15 @@ model TeamEnvironment {
 }
 
 model User {
-  uid              String            @id @default(cuid())
-  displayName      String?
-  email            String?
-  photoURL         String?
-  settings         UserSettings?
-
-  UserHistory UserHistory[]
-  UserEnvironments UserEnvironment[]
+  uid                String            @id @default(cuid())
+  displayName        String?
+  email              String?
+  photoURL           String?
+  currentRESTSession Json?
+  currentGQLSession  Json?
+  settings           UserSettings?
+  UserHistory        UserHistory[]
+  UserEnvironments   UserEnvironment[]
 }
 
 model UserSettings {
@@ -105,7 +106,7 @@ model UserHistory {
   request          Json
   responseMetadata Json
   isStarred        Boolean
-  executedOn       DateTime  @default(now()) @db.Timestamp(3)
+  executedOn       DateTime @default(now()) @db.Timestamp(3)
 }
 
 enum ReqType {
diff --git a/packages/hoppscotch-backend/src/errors.ts b/packages/hoppscotch-backend/src/errors.ts
index 117e6d0d..c78df062 100644
--- a/packages/hoppscotch-backend/src/errors.ts
+++ b/packages/hoppscotch-backend/src/errors.ts
@@ -26,6 +26,12 @@ export const USER_FB_DOCUMENT_DELETION_FAILED =
  */
 export const USER_NOT_FOUND = 'user/not_found' as const;
 
+/**
+ * User update failure
+ * (UserService)
+ */
+export const USER_UPDATE_FAILED = 'user/update_failed' as const;
+
 /**
  * User deletion failure
  * (UserService)
diff --git a/packages/hoppscotch-backend/src/prisma/prisma.service.ts b/packages/hoppscotch-backend/src/prisma/prisma.service.ts
index 8febf1b5..be48954e 100644
--- a/packages/hoppscotch-backend/src/prisma/prisma.service.ts
+++ b/packages/hoppscotch-backend/src/prisma/prisma.service.ts
@@ -16,4 +16,4 @@ export class PrismaService
   async onModuleDestroy() {
     await this.$disconnect();
   }
-}
+}
\ No newline at end of file
diff --git a/packages/hoppscotch-backend/src/pubsub/topicsDefs.ts b/packages/hoppscotch-backend/src/pubsub/topicsDefs.ts
index 8254b184..cee33860 100644
--- a/packages/hoppscotch-backend/src/pubsub/topicsDefs.ts
+++ b/packages/hoppscotch-backend/src/pubsub/topicsDefs.ts
@@ -1,3 +1,4 @@
+import { User } from 'src/user/user.model';
 import { UserSettings } from 'src/user-settings/user-settings.model';
 import { UserEnvironment } from '../user-environment/user-environments.model';
 import { UserHistory } from '../user-history/user-history.model';
@@ -5,10 +6,11 @@ import { UserHistory } from '../user-history/user-history.model';
 // A custom message type that defines the topic and the corresponding payload.
 // For every module that publishes a subscription add its type def and the possible subscription type.
 export type TopicDef = {
+  [topic: `user/${string}/${'updated'}`]: User;
+  [topic: `user_settings/${string}/${'created' | 'updated'}`]: UserSettings;
   [
     topic: `user_environment/${string}/${'created' | 'updated' | 'deleted'}`
   ]: UserEnvironment;
-  [topic: `user_settings/${string}/${'created' | 'updated'}`]: UserSettings;
   [topic: `user_environment/${string}/deleted_many`]: number;
   [
     topic: `user_history/${string}/${'created' | 'updated' | 'deleted'}`
diff --git a/packages/hoppscotch-backend/src/user/user.model.ts b/packages/hoppscotch-backend/src/user/user.model.ts
index 779dbc4d..d0631935 100644
--- a/packages/hoppscotch-backend/src/user/user.model.ts
+++ b/packages/hoppscotch-backend/src/user/user.model.ts
@@ -1,27 +1,54 @@
-import { ObjectType, ID, Field } from '@nestjs/graphql';
+import {
+  ObjectType,
+  ID,
+  Field,
+  InputType,
+  registerEnumType,
+} from '@nestjs/graphql';
 
 @ObjectType()
 export class User {
   @Field(() => ID, {
-    description: 'Firebase UID of the user',
+    description: 'UID of the user',
   })
   uid: string;
 
   @Field({
     nullable: true,
-    description: 'Displayed name of the user (if given)',
+    description: 'Displayed name of the user',
   })
   displayName?: string;
 
   @Field({
     nullable: true,
-    description: 'Email of the user (if given)',
+    description: 'Email of the user',
   })
   email?: string;
 
   @Field({
     nullable: true,
-    description: 'URL to the profile photo of the user (if given)',
+    description: 'URL to the profile photo of the user',
   })
   photoURL?: string;
+
+  @Field({
+    nullable: true,
+    description: 'Stringified current REST session for logged-in User',
+  })
+  currentRESTSession?: string;
+
+  @Field({
+    nullable: true,
+    description: 'Stringified current GraphQL session for logged-in User',
+  })
+  currentGQLSession?: string;
 }
+
+export enum SessionType {
+  REST = 'REST',
+  GQL = 'GQL',
+}
+
+registerEnumType(SessionType, {
+  name: 'SessionType',
+});
diff --git a/packages/hoppscotch-backend/src/user/user.module.ts b/packages/hoppscotch-backend/src/user/user.module.ts
index 3681faad..a5f9eda1 100644
--- a/packages/hoppscotch-backend/src/user/user.module.ts
+++ b/packages/hoppscotch-backend/src/user/user.module.ts
@@ -1,10 +1,12 @@
 import { Module } from '@nestjs/common';
 import { UserResolver } from './user.resolver';
 import { PubSubModule } from 'src/pubsub/pubsub.module';
+import { PrismaModule } from 'src/prisma/prisma.module';
+import { UserService } from './user.service';
 
 @Module({
-  imports: [PubSubModule],
-  providers: [UserResolver],
+  imports: [PubSubModule, PrismaModule],
+  providers: [UserResolver, UserService],
   exports: [],
 })
 export class UserModule {}
diff --git a/packages/hoppscotch-backend/src/user/user.resolver.ts b/packages/hoppscotch-backend/src/user/user.resolver.ts
index d913be01..a3c88fe2 100644
--- a/packages/hoppscotch-backend/src/user/user.resolver.ts
+++ b/packages/hoppscotch-backend/src/user/user.resolver.ts
@@ -1,14 +1,19 @@
-import { Resolver, Query } from '@nestjs/graphql';
-import { User } from './user.model';
+import { Resolver, Query, Mutation, Args, Subscription } from '@nestjs/graphql';
+import { SessionType, User } from './user.model';
 import { UseGuards } from '@nestjs/common';
 import { GqlAuthGuard } from '../guards/gql-auth.guard';
 import { GqlUser } from '../decorators/gql-user.decorator';
+import { UserService } from './user.service';
+import { throwErr } from 'src/utils';
+import * as E from 'fp-ts/lib/Either';
+import { PubSubService } from 'src/pubsub/pubsub.service';
 
 @Resolver(() => User)
 export class UserResolver {
-  // TODO: remove the eslint-disable line below once dependencies are added to user.service file
-  // eslint-disable-next-line @typescript-eslint/no-empty-function
-  constructor() {}
+  constructor(
+    private readonly userService: UserService,
+    private readonly pubsub: PubSubService,
+  ) {}
 
   @Query(() => User, {
     description:
@@ -27,4 +32,43 @@ export class UserResolver {
   me2(@GqlUser() user: User): User {
     return user;
   }
+
+  /* Mutations */
+
+  @Mutation(() => User, {
+    description: 'Update user sessions',
+  })
+  @UseGuards(GqlAuthGuard)
+  async updateUserSessions(
+    @GqlUser() user: User,
+    @Args({
+      name: 'currentSession',
+      description: 'JSON string of the saved REST/GQL session',
+    })
+    currentSession: string,
+    @Args({
+      name: 'sessionType',
+      description: 'Type of the session',
+    })
+    sessionType: SessionType,
+  ): Promise<User> {
+    const updatedUser = await this.userService.updateUserSessions(
+      user,
+      currentSession,
+      sessionType,
+    );
+    if (E.isLeft(updatedUser)) throwErr(updatedUser.left);
+    return updatedUser.right;
+  }
+
+  /* Subscriptions */
+
+  @Subscription(() => User, {
+    description: 'Listen for user updates',
+    resolve: (value) => value,
+  })
+  @UseGuards(GqlAuthGuard)
+  userUpdated(@GqlUser() user: User) {
+    return this.pubsub.asyncIterator(`user/${user.uid}/updated`);
+  }
 }
diff --git a/packages/hoppscotch-backend/src/user/user.service.spec.ts b/packages/hoppscotch-backend/src/user/user.service.spec.ts
new file mode 100644
index 00000000..4561a6f6
--- /dev/null
+++ b/packages/hoppscotch-backend/src/user/user.service.spec.ts
@@ -0,0 +1,108 @@
+import { mockDeep, mockReset } from 'jest-mock-extended';
+import { JSON_INVALID } from 'src/errors';
+import { PrismaService } from 'src/prisma/prisma.service';
+import { PubSubService } from 'src/pubsub/pubsub.service';
+import { UserService } from './user.service';
+
+const mockPrisma = mockDeep<PrismaService>();
+const mockPubSub = mockDeep<PubSubService>();
+
+// @ts-ignore
+const userService = new UserService(mockPrisma, mockPubSub as any);
+
+const user = {
+  uid: '123',
+  displayName: 'John Doe',
+  email: 'test@hoppscotch.io',
+  photoURL: 'https://example.com/avatar.png',
+  currentRESTSession: JSON.stringify({}),
+  currentGQLSession: JSON.stringify({}),
+};
+
+beforeEach(() => {
+  mockReset(mockPrisma);
+  mockPubSub.publish.mockClear();
+});
+
+describe('UserService', () => {
+  describe('updateUserSessions', () => {
+    test('Should resolve right and update users GQL session', async () => {
+      const sessionData = user.currentGQLSession;
+      mockPrisma.user.update.mockResolvedValue({
+        ...user,
+        currentGQLSession: JSON.parse(sessionData),
+        currentRESTSession: null,
+      });
+
+      const result = await userService.updateUserSessions(
+        user,
+        sessionData,
+        'GQL',
+      );
+
+      expect(result).toEqualRight({
+        ...user,
+        currentGQLSession: sessionData,
+        currentRESTSession: null,
+      });
+    });
+    test('Should resolve right and update users REST session', async () => {
+      const sessionData = user.currentGQLSession;
+      mockPrisma.user.update.mockResolvedValue({
+        ...user,
+        currentGQLSession: null,
+        currentRESTSession: JSON.parse(sessionData),
+      });
+
+      const result = await userService.updateUserSessions(
+        user,
+        sessionData,
+        'REST',
+      );
+
+      expect(result).toEqualRight({
+        ...user,
+        currentGQLSession: null,
+        currentRESTSession: sessionData,
+      });
+    });
+    test('Should reject left and update user for invalid GQL session', async () => {
+      const sessionData = 'invalid json';
+
+      const result = await userService.updateUserSessions(
+        user,
+        sessionData,
+        'GQL',
+      );
+
+      expect(result).toEqualLeft(JSON_INVALID);
+    });
+    test('Should reject left and update user for invalid REST session', async () => {
+      const sessionData = 'invalid json';
+
+      const result = await userService.updateUserSessions(
+        user,
+        sessionData,
+        'REST',
+      );
+
+      expect(result).toEqualLeft(JSON_INVALID);
+    });
+
+    test('Should publish pubsub message on user update sessions', async () => {
+      mockPrisma.user.update.mockResolvedValue({
+        ...user,
+        currentGQLSession: JSON.parse(user.currentGQLSession),
+        currentRESTSession: JSON.parse(user.currentRESTSession),
+      });
+
+      await userService.updateUserSessions(user, user.currentGQLSession, 'GQL');
+
+      expect(mockPubSub.publish).toHaveBeenCalledTimes(1);
+      expect(mockPubSub.publish).toHaveBeenCalledWith(
+        `user/${user.uid}/updated`,
+        user,
+      );
+    });
+  });
+});
diff --git a/packages/hoppscotch-backend/src/user/user.service.ts b/packages/hoppscotch-backend/src/user/user.service.ts
new file mode 100644
index 00000000..9b0d6be1
--- /dev/null
+++ b/packages/hoppscotch-backend/src/user/user.service.ts
@@ -0,0 +1,79 @@
+import { Injectable } from '@nestjs/common';
+import { PrismaService } from '../prisma/prisma.service';
+import { SessionType, User } from './user.model';
+import * as E from 'fp-ts/lib/Either';
+import { USER_UPDATE_FAILED } from 'src/errors';
+import { PubSubService } from 'src/pubsub/pubsub.service';
+import { stringToJson } from 'src/utils';
+
+@Injectable()
+export class UserService {
+  constructor(
+    private readonly prisma: PrismaService,
+    private readonly pubsub: PubSubService,
+  ) {}
+
+  /**
+   * Update a user's sessions
+   * @param user User object
+   * @param currentRESTSession user's current REST session
+   * @param currentGQLSession user's current GQL session
+   * @returns a Either of User or error
+   */
+  async updateUserSessions(
+    user: User,
+    currentSession: string,
+    sessionType: string,
+  ): Promise<E.Right<User> | E.Left<string>> {
+    const validatedSession = await this.validateSession(currentSession);
+    if (E.isLeft(validatedSession)) return E.left(validatedSession.left);
+
+    try {
+      const sessionObj = {};
+      switch (sessionType) {
+        case SessionType.GQL:
+          sessionObj['currentGQLSession'] = validatedSession.right;
+          break;
+        case SessionType.REST:
+          sessionObj['currentRESTSession'] = validatedSession.right;
+          break;
+        default:
+          return E.left(USER_UPDATE_FAILED);
+      }
+
+      const dbUpdatedUser = await this.prisma.user.update({
+        where: { uid: user.uid },
+        data: sessionObj,
+      });
+
+      const updatedUser: User = {
+        ...dbUpdatedUser,
+        currentGQLSession: dbUpdatedUser.currentGQLSession
+          ? JSON.stringify(dbUpdatedUser.currentGQLSession)
+          : null,
+        currentRESTSession: dbUpdatedUser.currentRESTSession
+          ? JSON.stringify(dbUpdatedUser.currentRESTSession)
+          : null,
+      };
+
+      // Publish subscription for user updates
+      await this.pubsub.publish(`user/${updatedUser.uid}/updated`, updatedUser);
+
+      return E.right(updatedUser);
+    } catch (e) {
+      return E.left(USER_UPDATE_FAILED);
+    }
+  }
+
+  /**
+   * Validate and parse currentRESTSession and currentGQLSession
+   * @param sessionData string of the session
+   * @returns a Either of JSON object or error
+   */
+  async validateSession(sessionData: string) {
+    const jsonSession = stringToJson(sessionData);
+    if (E.isLeft(jsonSession)) return E.left(jsonSession.left);
+
+    return E.right(jsonSession.right);
+  }
+}