Senior Android Engineer

You'll be the sole Android engineer owning a mature, modular social platform used daily by ~250k active users worldwide — a full-featured messenger with 1:1 and group chats, a social timeline, stories, audio/video calls, push notifications, and broadcast.

The codebase spans ~37 Gradle modules and over 300k lines of code, with both legacy and modern paradigms running side by side.

This is not a greenfield project. It's a living system that requires someone who can navigate complexity, make architectural decisions without a second pair of eyes, and keep shipping — while steadily modernizing what's already there.

Key responsibilities

1. Own the Android codebase end-to-end — architecture decisions, code review, releases, and production monitoring.

2. Maintain and evolve a multi-module Gradle project (~37 modules, 300k+ LOC), balancing feature delivery with controlled technical debt reduction.

3. Drive incremental migration from legacy patterns (RxJava → Coroutines, Views → Compose) without breaking production.

4. Operate real-time features — WebRTC-based audio/video calls, signaling, push notifications, foreground services.

5. Own the CI/CD pipeline on GitLab CI — build stages, UI tests, staged rollouts via Google Play Console.

6. Maintain and improve the testing suite — unit, instrumented, Compose, screenshot, Macrobenchmark, and E2E.

7. Keep operational documentation up to date: ADRs, feature descriptions, release notes.

8. Collaborate cross-team with backend (API contracts, protobuf), iOS (feature parity), and design (Figma, design system).

What we offer

• Salary:
  19.500 – 26.500 PLN net / B2B per month

• Remote first approach

• Transparent, async-first, documentation-driven organization

• AI engineering approach

What do we need for this position?

1. Ownership mindset — you're the only Android engineer on the project. Comfortable making architectural calls alone and living with the consequences.

2. Pragmatic about modernization — doesn't rewrite everything on day one; migrates with intent and impact in mind.

3. Writes things down. ADRs, release notes, onboarding docs — without being asked twice.

4. Communicates clearly with backend, iOS, and design teams, and directly with client stakeholders.

5. Self-disciplined about quality — rigorous testing and device verification before merge, because there's no second reviewer.

6. Asks why before how.

You'll be a great fit if you have:

• 6+ years of commercial Android experience in production apps at meaningful scale (100k+ MAU).

• 2+ years as a sole maintainer or tech lead — comfortable making decisions without a mentor or peer review.

• Expert-level Kotlin: coroutines, Flow, sealed classes, generics, type-safe builders.

• Production Jetpack Compose — state hoisting, recomposition, side effects, performance (stable/skippable, Baseline Profiles), Material 3.

• Solid RxJava 2 — not just reading, but writing and debugging Observables, Subjects, schedulers, backpressure.

• Dagger 2 in a multi-module project — modules, scopes, components, subcomponents, assisted injection.

• Gradle multi-module builds — version catalog, dependency conflict resolution, product flavors, build types, KSP.

• Network stack: OkHttp, WebSockets, Okio, Protocol Buffers (including shared .proto contracts with backend).

• Room, offline sync, cache strategies and mutation queues.

• CI/CD on GitLab CI — build, test, release stages, Google Play staged rollouts, Firebase App Distribution.

• Firebase: Crashlytics, Remote Config, Performance Monitoring, Test Lab.

• Full testing fluency: JUnit 4, Mockk, Strikt, Espresso, Compose tests, screenshot tests, Macrobenchmark, Gradle Managed Devices.

• Polish and English at B2+, written and spoken.

Nice to have:

• WebRTC in production — signaling, STUN/TURN, NAT traversal, call quality diagnostics.

• Experience with messaging or real-time apps (Signal, Telegram, Slack, Discord — comparable domain complexity).

• ExoPlayer/Media3, CameraX.

• Social feed experience: timeline, fan-out, mentions, link previews.

• ANR debugging and deep performance tuning.

• Experience writing AI-assisted development tools or agents.

• Bash/Python for build and test scripting.

• Material Design 3 — motion, color schemes, dynamic color.

• macOS as primary OS.

Our recruitment process

Only 3 steps long:

1. Culture & mission fit meeting with Recruitment Team (abt. 45 minutes)

2. Competency interview with team representatives (abt. 60 minutes)

3. AI fluency assessment via AI CRED (aicred.ai) — a short online test measuring competency across 5 AI dimensions.

4. If any other step of the recruitment process is necessary, we will inform you!

5. And finally, the decision — after which we can say "welcome on board."