diff --git a/backend/scripts/generate-openapi.ts b/backend/scripts/generate-openapi.ts
index add9966..3d17e5a 100644
--- a/backend/scripts/generate-openapi.ts
+++ b/backend/scripts/generate-openapi.ts
@@ -11,6 +11,9 @@ async function generate(): Promise<void> {
   process.env.STORAGE_ROOT ??= join(process.cwd(), '..', 'runtime', 'storage');
   process.env.PUBLIC_BASE_URL ??= 'http://localhost:3007';
   process.env.DEVICE_BOOTSTRAP_SECRET ??= 'openapi-placeholder-secret';
+  process.env.ACCOUNT_ACCESS_TOKEN_SECRET ??=
+    'openapi-placeholder-account-access-secret';
+  process.env.ACCOUNT_ACCESS_TOKEN_TTL_SECONDS ??= '900';
   process.env.MAX_UPLOAD_SIZE_BYTES ??= '524288000';
 
   const { createApp } = await import('../src/app.factory');
diff --git a/backend/src/modules/auth/access-token.service.spec.ts b/backend/src/modules/auth/access-token.service.spec.ts
new file mode 100644
index 0000000..67e25ca
--- /dev/null
+++ b/backend/src/modules/auth/access-token.service.spec.ts
@@ -0,0 +1,243 @@
+import { randomUUID, createHmac } from 'node:crypto';
+import { UnauthorizedException } from '@nestjs/common';
+import { AccountSessionStatus } from '@prisma/client';
+import { AppConfigService } from '../config/config.service';
+import {
+  AccessTokenService,
+  AccountAccessTokenClaims,
+} from './access-token.service';
+import { SessionService } from './session.service';
+
+describe('AccessTokenService', () => {
+  const signingSecret = 'test-account-access-signing-secret';
+  const now = new Date('2026-06-28T12:00:00.000Z');
+  const userId = randomUUID();
+  const sessionId = randomUUID();
+
+  const signPayload = (
+    payload: Record<string, unknown>,
+    secret = signingSecret,
+    header: Record<string, unknown> = { alg: 'HS256', typ: 'JWT' },
+  ): string => {
+    const encodedHeader = Buffer.from(JSON.stringify(header)).toString(
+      'base64url',
+    );
+    const encodedPayload = Buffer.from(JSON.stringify(payload)).toString(
+      'base64url',
+    );
+    const signingInput = `${encodedHeader}.${encodedPayload}`;
+    const signature = createHmac('sha256', secret)
+      .update(signingInput)
+      .digest('base64url');
+
+    return `${signingInput}.${signature}`;
+  };
+
+  const buildService = () => {
+    let currentAccessTokenVersion = 1;
+    let sessionStatus: AccountSessionStatus = AccountSessionStatus.ACTIVE;
+    const sessionService = {
+      validateSession: jest.fn().mockImplementation(async (input) => {
+        if (
+          sessionStatus !== AccountSessionStatus.ACTIVE ||
+          input.sessionId !== sessionId ||
+          input.accessTokenVersion !== currentAccessTokenVersion
+        ) {
+          throw new UnauthorizedException('Session is invalid');
+        }
+
+        return {
+          id: sessionId,
+          userId,
+          refreshTokenHash: 'stored-refresh-token-hash',
+          status: sessionStatus,
+          accessTokenVersion: currentAccessTokenVersion,
+          expiresAt: new Date('2026-07-28T12:00:00.000Z'),
+          lastRefreshedAt: null,
+          revokedAt: null,
+          createdAt: now,
+          updatedAt: now,
+        };
+      }),
+    } as unknown as SessionService;
+    const configService = {
+      accountAccessTokenSecret: signingSecret,
+      accountAccessTokenTtlSeconds: 900,
+    } as AppConfigService;
+    const service = new AccessTokenService(configService, sessionService);
+
+    return {
+      service,
+      sessionService,
+      setCurrentAccessTokenVersion: (version: number) => {
+        currentAccessTokenVersion = version;
+      },
+      setSessionStatus: (status: AccountSessionStatus) => {
+        sessionStatus = status;
+      },
+    };
+  };
+
+  const issueToken = (service: AccessTokenService): string =>
+    service.issueAccessToken(
+      {
+        userId,
+        sessionId,
+        accessTokenVersion: 1,
+      },
+      now,
+    );
+
+  it('issues a signed token with the required account claims', () => {
+    const { service } = buildService();
+
+    const token = issueToken(service);
+    const payload = service.decodeAccessToken(token);
+
+    expect(payload).toEqual({
+      sub: userId,
+      sid: sessionId,
+      ver: 1,
+      typ: 'account_access',
+      iat: Math.floor(now.getTime() / 1000),
+      exp: Math.floor(now.getTime() / 1000) + 900,
+    });
+  });
+
+  it('verifies a valid token and its backing session', async () => {
+    const { service, sessionService } = buildService();
+    const token = issueToken(service);
+
+    await expect(service.verifyAccessToken(token, now)).resolves.toMatchObject({
+      sub: userId,
+      sid: sessionId,
+      ver: 1,
+      typ: 'account_access',
+    });
+    expect(sessionService.validateSession).toHaveBeenCalledWith(
+      {
+        sessionId,
+        accessTokenVersion: 1,
+      },
+      now,
+    );
+  });
+
+  it('rejects an expired token before session validation', async () => {
+    const { service, sessionService } = buildService();
+    const token = issueToken(service);
+    const expiration = new Date(now.getTime() + 900_000);
+
+    await expect(
+      service.verifyAccessToken(token, expiration),
+    ).rejects.toThrow(UnauthorizedException);
+    expect(sessionService.validateSession).not.toHaveBeenCalled();
+  });
+
+  it('rejects a token with the wrong account token type', async () => {
+    const { service } = buildService();
+    const token = signPayload({
+      sub: userId,
+      sid: sessionId,
+      ver: 1,
+      typ: 'device_access',
+      iat: Math.floor(now.getTime() / 1000),
+      exp: Math.floor(now.getTime() / 1000) + 900,
+    });
+
+    await expect(service.verifyAccessToken(token, now)).rejects.toThrow(
+      UnauthorizedException,
+    );
+  });
+
+  it('rejects a stale token version after session refresh', async () => {
+    const { service, setCurrentAccessTokenVersion } = buildService();
+    const token = issueToken(service);
+    setCurrentAccessTokenVersion(2);
+
+    await expect(service.verifyAccessToken(token, now)).rejects.toThrow(
+      UnauthorizedException,
+    );
+  });
+
+  it('rejects a token backed by a revoked session', async () => {
+    const { service, setSessionStatus } = buildService();
+    const token = issueToken(service);
+    setSessionStatus(AccountSessionStatus.REVOKED);
+
+    await expect(service.verifyAccessToken(token, now)).rejects.toThrow(
+      UnauthorizedException,
+    );
+  });
+
+  it('rejects a token backed by an expired session', async () => {
+    const { service, setSessionStatus } = buildService();
+    const token = issueToken(service);
+    setSessionStatus(AccountSessionStatus.EXPIRED);
+
+    await expect(service.verifyAccessToken(token, now)).rejects.toThrow(
+      UnauthorizedException,
+    );
+  });
+
+  it('rejects a token signed with a different secret', async () => {
+    const { service, sessionService } = buildService();
+    const payload: AccountAccessTokenClaims = {
+      sub: userId,
+      sid: sessionId,
+      ver: 1,
+      typ: 'account_access',
+      iat: Math.floor(now.getTime() / 1000),
+      exp: Math.floor(now.getTime() / 1000) + 900,
+    };
+    const token = signPayload({ ...payload }, 'different-signing-secret');
+
+    await expect(service.verifyAccessToken(token, now)).rejects.toThrow(
+      UnauthorizedException,
+    );
+    expect(sessionService.validateSession).not.toHaveBeenCalled();
+  });
+
+  it('does not expose email, password, or refresh token data', () => {
+    const { service } = buildService();
+
+    const payload = service.decodeAccessToken(issueToken(service));
+
+    expect(payload).not.toHaveProperty('email');
+    expect(payload).not.toHaveProperty('password');
+    expect(payload).not.toHaveProperty('passwordHash');
+    expect(payload).not.toHaveProperty('refreshToken');
+    expect(payload).not.toHaveProperty('refreshTokenHash');
+  });
+
+  it.each([
+    ['sub', { sid: sessionId }],
+    ['sid', { sub: userId }],
+  ])('rejects a token missing %s', async (_claim, identityClaims) => {
+    const { service } = buildService();
+    const token = signPayload({
+      ...identityClaims,
+      ver: 1,
+      typ: 'account_access',
+      iat: Math.floor(now.getTime() / 1000),
+      exp: Math.floor(now.getTime() / 1000) + 900,
+    });
+
+    await expect(service.verifyAccessToken(token, now)).rejects.toThrow(
+      UnauthorizedException,
+    );
+  });
+
+  it('rejects a valid session that belongs to a different subject', async () => {
+    const { service, sessionService } = buildService();
+    (sessionService.validateSession as jest.Mock).mockResolvedValue({
+      id: sessionId,
+      userId: randomUUID(),
+    });
+    const token = issueToken(service);
+
+    await expect(service.verifyAccessToken(token, now)).rejects.toThrow(
+      UnauthorizedException,
+    );
+  });
+});
diff --git a/backend/src/modules/auth/access-token.service.ts b/backend/src/modules/auth/access-token.service.ts
new file mode 100644
index 0000000..eb8782e
--- /dev/null
+++ b/backend/src/modules/auth/access-token.service.ts
@@ -0,0 +1,186 @@
+import { Injectable, UnauthorizedException } from '@nestjs/common';
+import { createHmac, timingSafeEqual } from 'node:crypto';
+import { AppConfigService } from '../config/config.service';
+import { SessionService } from './session.service';
+
+const ACCOUNT_ACCESS_TOKEN_TYPE = 'account_access' as const;
+const JWT_ALGORITHM = 'HS256' as const;
+
+interface JwtHeader {
+  alg: typeof JWT_ALGORITHM;
+  typ: 'JWT';
+}
+
+export interface IssueAccessTokenInput {
+  userId: string;
+  sessionId: string;
+  accessTokenVersion: number;
+}
+
+export interface AccountAccessTokenClaims {
+  sub: string;
+  sid: string;
+  ver: number;
+  typ: typeof ACCOUNT_ACCESS_TOKEN_TYPE;
+  iat: number;
+  exp: number;
+}
+
+export type DecodedAccessTokenPayload = Record<string, unknown>;
+
+@Injectable()
+export class AccessTokenService {
+  constructor(
+    private readonly configService: AppConfigService,
+    private readonly sessionService: SessionService,
+  ) {}
+
+  issueAccessToken(input: IssueAccessTokenInput, now = new Date()): string {
+    const issuedAt = Math.floor(now.getTime() / 1000);
+    const claims: AccountAccessTokenClaims = {
+      sub: input.userId,
+      sid: input.sessionId,
+      ver: input.accessTokenVersion,
+      typ: ACCOUNT_ACCESS_TOKEN_TYPE,
+      iat: issuedAt,
+      exp: issuedAt + this.configService.accountAccessTokenTtlSeconds,
+    };
+
+    const header: JwtHeader = {
+      alg: JWT_ALGORITHM,
+      typ: 'JWT',
+    };
+    const encodedHeader = this.encodeJson(header);
+    const encodedPayload = this.encodeJson(claims);
+    const signingInput = `${encodedHeader}.${encodedPayload}`;
+    const signature = this.sign(signingInput);
+
+    return `${signingInput}.${signature}`;
+  }
+
+  async verifyAccessToken(
+    token: string,
+    now = new Date(),
+  ): Promise<AccountAccessTokenClaims> {
+    const [encodedHeader, encodedPayload, encodedSignature] =
+      this.splitToken(token);
+    const header = this.decodeJson(encodedHeader);
+
+    if (header.alg !== JWT_ALGORITHM || header.typ !== 'JWT') {
+      throw this.invalidToken();
+    }
+
+    const expectedSignature = this.sign(
+      `${encodedHeader}.${encodedPayload}`,
+    );
+    const suppliedSignature = Buffer.from(encodedSignature, 'utf8');
+    const expectedSignatureBytes = Buffer.from(expectedSignature, 'utf8');
+
+    if (
+      suppliedSignature.length !== expectedSignatureBytes.length ||
+      !timingSafeEqual(suppliedSignature, expectedSignatureBytes)
+    ) {
+      throw this.invalidToken();
+    }
+
+    const claims = this.assertClaims(this.decodeJson(encodedPayload), now);
+    await this.assertAccessTokenSession(claims, now);
+
+    return claims;
+  }
+
+  decodeAccessToken(token: string): DecodedAccessTokenPayload {
+    const [, encodedPayload] = this.splitToken(token);
+    return this.decodeJson(encodedPayload);
+  }
+
+  async assertAccessTokenSession(
+    claims: AccountAccessTokenClaims,
+    now = new Date(),
+  ): Promise<void> {
+    const session = await this.sessionService.validateSession(
+      {
+        sessionId: claims.sid,
+        accessTokenVersion: claims.ver,
+      },
+      now,
+    );
+
+    if (session.userId !== claims.sub) {
+      throw this.invalidToken();
+    }
+  }
+
+  private assertClaims(
+    payload: DecodedAccessTokenPayload,
+    now: Date,
+  ): AccountAccessTokenClaims {
+    if (
+      payload.typ !== ACCOUNT_ACCESS_TOKEN_TYPE ||
+      typeof payload.sub !== 'string' ||
+      payload.sub.length === 0 ||
+      typeof payload.sid !== 'string' ||
+      payload.sid.length === 0 ||
+      typeof payload.ver !== 'number' ||
+      !Number.isInteger(payload.ver) ||
+      payload.ver < 1 ||
+      typeof payload.iat !== 'number' ||
+      !Number.isInteger(payload.iat) ||
+      typeof payload.exp !== 'number' ||
+      !Number.isInteger(payload.exp) ||
+      payload.exp <= Math.floor(now.getTime() / 1000)
+    ) {
+      throw this.invalidToken();
+    }
+
+    return payload as unknown as AccountAccessTokenClaims;
+  }
+
+  private splitToken(token: string): [string, string, string] {
+    const segments = token.split('.');
+
+    if (
+      segments.length !== 3 ||
+      !segments[0] ||
+      !segments[1] ||
+      !segments[2]
+    ) {
+      throw this.invalidToken();
+    }
+
+    return [segments[0], segments[1], segments[2]];
+  }
+
+  private decodeJson(segment: string): DecodedAccessTokenPayload {
+    try {
+      const decoded: unknown = JSON.parse(
+        Buffer.from(segment, 'base64url').toString('utf8'),
+      );
+
+      if (!decoded || typeof decoded !== 'object' || Array.isArray(decoded)) {
+        throw this.invalidToken();
+      }
+
+      return decoded as DecodedAccessTokenPayload;
+    } catch {
+      throw this.invalidToken();
+    }
+  }
+
+  private encodeJson(value: JwtHeader | AccountAccessTokenClaims): string {
+    return Buffer.from(JSON.stringify(value), 'utf8').toString('base64url');
+  }
+
+  private sign(signingInput: string): string {
+    return createHmac(
+      'sha256',
+      this.configService.accountAccessTokenSecret,
+    )
+      .update(signingInput)
+      .digest('base64url');
+  }
+
+  private invalidToken(): UnauthorizedException {
+    return new UnauthorizedException('Invalid account access token');
+  }
+}
diff --git a/backend/src/modules/auth/auth.module.ts b/backend/src/modules/auth/auth.module.ts
index 3a56c26..ccdf99b 100644
--- a/backend/src/modules/auth/auth.module.ts
+++ b/backend/src/modules/auth/auth.module.ts
@@ -2,6 +2,7 @@ import { MiddlewareConsumer, Module, NestModule } from '@nestjs/common';
 import { PrismaModule } from '../../infrastructure/database/prisma.module';
 import { RequestContextMiddleware } from '../../infrastructure/request-context/request-context.middleware';
 import { RequestContextModule } from '../../infrastructure/request-context/request-context.module';
+import { AccessTokenService } from './access-token.service';
 import { DeviceAuthGuard } from './device-auth.guard';
 import { DeviceAuthService } from './device-auth.service';
 import { OptionalDeviceAuthGuard } from './optional-device-auth.guard';
@@ -11,6 +12,7 @@ import { SessionService } from './session.service';
 @Module({
   imports: [PrismaModule, RequestContextModule],
   providers: [
+    AccessTokenService,
     DeviceAuthService,
     DeviceAuthGuard,
     OptionalDeviceAuthGuard,
@@ -18,6 +20,7 @@ import { SessionService } from './session.service';
     SessionService,
   ],
   exports: [
+    AccessTokenService,
     DeviceAuthService,
     DeviceAuthGuard,
     OptionalDeviceAuthGuard,
diff --git a/backend/src/modules/config/config.service.ts b/backend/src/modules/config/config.service.ts
index f1a0122..807acad 100644
--- a/backend/src/modules/config/config.service.ts
+++ b/backend/src/modules/config/config.service.ts
@@ -29,6 +29,14 @@ export class AppConfigService {
     return this.required('DEVICE_BOOTSTRAP_SECRET');
   }
 
+  get accountAccessTokenSecret(): string {
+    return this.required('ACCOUNT_ACCESS_TOKEN_SECRET');
+  }
+
+  get accountAccessTokenTtlSeconds(): number {
+    return Number(this.required('ACCOUNT_ACCESS_TOKEN_TTL_SECONDS'));
+  }
+
   get maxUploadSizeBytes(): number {
     return Number(this.required('MAX_UPLOAD_SIZE_BYTES'));
   }
diff --git a/backend/src/modules/config/environment.spec.ts b/backend/src/modules/config/environment.spec.ts
index 50c9c7b..7b3ef54 100644
--- a/backend/src/modules/config/environment.spec.ts
+++ b/backend/src/modules/config/environment.spec.ts
@@ -8,11 +8,14 @@ describe('validateEnvironment', () => {
       DATABASE_URL: 'postgresql://velody:velody@localhost:5432/velody?schema=public',
       STORAGE_ROOT: '/tmp/velody',
       PUBLIC_BASE_URL: 'http://localhost:3007',
-      DEVICE_BOOTSTRAP_SECRET: 'secret',
+      DEVICE_BOOTSTRAP_SECRET: 'device-secret',
+      ACCOUNT_ACCESS_TOKEN_SECRET: 'account-secret',
+      ACCOUNT_ACCESS_TOKEN_TTL_SECONDS: '900',
       MAX_UPLOAD_SIZE_BYTES: '1024',
     });
 
     expect(result.PORT).toBe(3007);
+    expect(result.ACCOUNT_ACCESS_TOKEN_TTL_SECONDS).toBe(900);
     expect(result.MAX_UPLOAD_SIZE_BYTES).toBe(1024);
   });
 
@@ -23,4 +26,21 @@ describe('validateEnvironment', () => {
       }),
     ).toThrow(/Invalid environment configuration/);
   });
+
+  it('rejects reuse of the device-token secret for account tokens', () => {
+    expect(() =>
+      validateEnvironment({
+        NODE_ENV: 'test',
+        PORT: '3007',
+        DATABASE_URL:
+          'postgresql://velody:velody@localhost:5432/velody?schema=public',
+        STORAGE_ROOT: '/tmp/velody',
+        PUBLIC_BASE_URL: 'http://localhost:3007',
+        DEVICE_BOOTSTRAP_SECRET: 'shared-secret',
+        ACCOUNT_ACCESS_TOKEN_SECRET: 'shared-secret',
+        ACCOUNT_ACCESS_TOKEN_TTL_SECONDS: '900',
+        MAX_UPLOAD_SIZE_BYTES: '1024',
+      }),
+    ).toThrow(/account and device token secrets must be different/);
+  });
 });
diff --git a/backend/src/modules/config/environment.ts b/backend/src/modules/config/environment.ts
index 1ffc9ff..76c4541 100644
--- a/backend/src/modules/config/environment.ts
+++ b/backend/src/modules/config/environment.ts
@@ -37,6 +37,14 @@ class EnvironmentVariables {
   @IsNotEmpty()
   DEVICE_BOOTSTRAP_SECRET!: string;
 
+  @IsString()
+  @IsNotEmpty()
+  ACCOUNT_ACCESS_TOKEN_SECRET!: string;
+
+  @IsInt()
+  @Min(1)
+  ACCOUNT_ACCESS_TOKEN_TTL_SECONDS!: number;
+
   @IsInt()
   @Min(1)
   MAX_UPLOAD_SIZE_BYTES!: number;
@@ -59,6 +67,15 @@ export function validateEnvironment(config: Record<string, unknown>) {
     );
   }
 
+  if (
+    validated.ACCOUNT_ACCESS_TOKEN_SECRET ===
+    validated.DEVICE_BOOTSTRAP_SECRET
+  ) {
+    throw new Error(
+      'Invalid environment configuration: account and device token secrets must be different',
+    );
+  }
+
   return validated;
 }
 
diff --git a/backend/test/setup-env.ts b/backend/test/setup-env.ts
index 1568c1e..09a45cc 100644
--- a/backend/test/setup-env.ts
+++ b/backend/test/setup-env.ts
@@ -11,5 +11,9 @@ process.env.PUBLIC_BASE_URL =
   process.env.PUBLIC_BASE_URL ?? 'http://localhost:3007';
 process.env.DEVICE_BOOTSTRAP_SECRET =
   process.env.DEVICE_BOOTSTRAP_SECRET ?? 'test-secret';
+process.env.ACCOUNT_ACCESS_TOKEN_SECRET =
+  process.env.ACCOUNT_ACCESS_TOKEN_SECRET ?? 'test-account-access-secret';
+process.env.ACCOUNT_ACCESS_TOKEN_TTL_SECONDS =
+  process.env.ACCOUNT_ACCESS_TOKEN_TTL_SECONDS ?? '900';
 process.env.MAX_UPLOAD_SIZE_BYTES =
   process.env.MAX_UPLOAD_SIZE_BYTES ?? '1073741824';
diff --git a/infra/docker/env/backend.env.example b/infra/docker/env/backend.env.example
index 5cc1d18..ed397ef 100644
--- a/infra/docker/env/backend.env.example
+++ b/infra/docker/env/backend.env.example
@@ -4,4 +4,6 @@ DATABASE_URL=postgresql://velody:velody@postgres:5432/velody?schema=public
 STORAGE_ROOT=/app/runtime/storage
 PUBLIC_BASE_URL=http://localhost:3007
 DEVICE_BOOTSTRAP_SECRET=replace-me
+ACCOUNT_ACCESS_TOKEN_SECRET=replace-with-a-distinct-secret
+ACCOUNT_ACCESS_TOKEN_TTL_SECONDS=900
 MAX_UPLOAD_SIZE_BYTES=524288000