Senior Mobile Engineer (Swift and/or Kotlin)

Quick Facts

• Role: Senior Mobile Engineer (Swift and/or Kotlin)

Description

Build and modernize native iOS and/or Android apps for regulated clients where releases are high-stakes. You will own mobile architecture, testing/CI/CD, and server-driven UI so product teams can ship new journeys without full app releases. You’ll use AI-assisted development daily and integrate securely end to end with backend services.

Responsibilities

• Design and build native apps using Swift (SwiftUI, UIKit) and/or Kotlin (Jetpack Compose), including new features, modernization, and justified rewrites
• Own platform architecture (modularization, MVVM / Clean Architecture / TCA, dependency injection, offline-first and data sync)
• Build and evolve server-driven UI using component schemas (JSON or Protobuf), client-side rendering, schema versioning, backward compatibility, and fallbacks
• Apply AI-driven development (coding agents/copilots) for implementation, refactoring, test generation, and code review; verify and own outputs
• Integrate with backend services (REST, GraphQL, gRPC) and secure the app end to end (OAuth2/OIDC, biometrics, secure storage, certificate pinning, root/jailbreak detection, OWASP MASVS)
• Set engineering standards and manage delivery (code review, unit/UI/snapshot tests, CI/CD, signing, and phased rollouts to stores)
• Improve observability and product quality (crash reporting, analytics, feature flags, performance and startup-time budgets)
• Deliver accessibility (WCAG 2.2 / EN 301 549) and localization for regulated clients
• Collaborate with product/design/backend/QA; estimate, plan, and demo work to stakeholders
• Mentor mid-level engineers and support proposals/pre-sales demos

Requirements

• 6+ years of native mobile development, including 3+ years in Swift (iOS) and/or Kotlin (Android)
• Shipped at least two native apps to production and maintained them across multiple releases
• Deep platform knowledge: iOS (SwiftUI/UIKit, Swift Concurrency or Combine, Xcode toolchain) and/or Android (Jetpack Compose, Kotlin Coroutines/Flow, Android Jetpack, Gradle) with working knowledge of the other platform
• Hands-on mobile security experience in regulated environments: OAuth2/OIDC and strong customer authentication, secure storage, certificate pinning, OWASP MASVS, and addressing pen-test findings
• Strong testing and CI/CD practice (XCTest/JUnit, UI and snapshot tests, automated pipelines, code signing, store submission and release management)
• Proven ability to own architecture decisions and safely refactor large legacy codebases
• Experience with server-driven UI (component schemas, client renderer, schema versioning, A/B layouts; awareness of offline/performance/accessibility trade-offs)
• Ability to use AI-driven development daily and review AI-generated code to the same standard as your own
• API integration experience with REST and GraphQL and OpenAPI contracts; collaboration on API design
• Experience in banking/insurance/fintech or healthcare, including PII handling and regulatory constraints (PSD2/SCA, GDPR)
• Clear communication with non-engineers (trade-offs, estimation)
• Full professional fluency in Polish and English

Benefits

• Real ownership of the apps you build with direct access to client product owners
• Competitive B2B contract compensation
• Annual training and certification budget
• Remote work with access to a central Warsaw office
• Opportunity to shape a young firm’s mobile practice, engineering standards, hiring, and culture