Senior Mobile Engineer (Swift and/or Kotlin)

Exerizon is a fast-growing strategy and technology consulting firm founded by former senior leaders from global consulting and cloud organizations. We help current and future market leaders tackle their greatest challenges — from digital strategy and cloud transformation to data & AI platforms and application modernization. We redefined the traditional consulting model: we share risk with our clients through impact-based remuneration, and we share ownership with our people from day one. We are looking for a Senior Mobile Engineer to build and modernise native mobile apps for our clients in banking, insurance and healthcare — on iOS (Swift), Android (Kotlin), or both. You will work on apps that are the client's primary customer channel: high traffic, strict security and regulatory requirements, and real consequences when a release goes wrong. What you will do: - Design and build native apps in Swift (SwiftUI, UIKit) and/or Kotlin (Jetpack Compose) — new features, modernisation of legacy codebases, and rewrites where they are justified - Own the architecture on your platform: modularisation, MVVM / Clean Architecture / TCA, dependency injection, offline-first and data sync strategies - Build and evolve server-driven UI (SDUI): design component schemas with backend teams (JSON or Protobuf), own the client-side rendering engine, handle schema versioning, backward compatibility and graceful fallbacks — so product teams ship new journeys without an app release - Practise AI-driven development every day: coding agents and copilots (Claude Code, Cursor, GitHub Copilot) for implementation, refactoring, test generation and code review — with the judgement to verify and own what they produce, and the discipline to bring that practice to the whole team - Integrate with backend services (REST, GraphQL, gRPC) and secure the app end to end: OAuth2 / OIDC, biometrics, secure storage (Keychain, Keystore), certificate pinning, root and jailbreak detection, OWASP MASVS - Set and enforce engineering standards: code review, unit, UI and snapshot tests, CI/CD (Fastlane, GitHub Actions, Azure DevOps or Bitrise), signing, App Store and Google Play release management with phased rollouts - Build in observability and product quality: crash reporting, analytics, feature flags, performance and startup-time budgets - Deliver accessibility (WCAG 2.2 / EN 301 549) and localisation to the standard regulated clients require - Work directly with client product owners, designers, backend engineers and QA; estimate, plan and demo your work to stakeholders - Mentor mid-level engineers, raise the bar across Exerizon's mobile practice, and support proposals and pre-sales demos Requirements - 6+ years of native mobile development, including 3+ years in Swift (iOS) and/or Kotlin (Android); at least two apps shipped to production and maintained through multiple releases - Deep knowledge of your platform — iOS: SwiftUI and UIKit, Swift Concurrency or Combine, Xcode toolchain; Android: Jetpack Compose, Kotlin Coroutines and Flow, Android Jetpack, Gradle — with a working understanding of the other platform - Hands-on experience with mobile security in regulated environments: OAuth2 / OIDC and strong customer authentication flows, secure storage, certificate pinning, OWASP MASVS, and closing pen-test findings - Solid testing and CI/CD practice: XCTest or JUnit, UI and snapshot tests, automated pipelines, code signing, store submission and release management - Proven ability to own architecture decisions and refactor large legacy codebases safely, with measurable improvements in build time, crash rate or release cadence - Experience designing or integrating a server-driven UI framework: component schemas, a client renderer, schema versioning and A/B-tested layouts; you know where SDUI pays off and where it hurts (offline, performance, accessibility) - AI-driven development as part of your workflow: you use coding agents and copilots daily, understand their failure modes, and review AI-generated code to the same standard as your own - Fluent in API integration: REST and GraphQL, OpenAPI contracts, and working with backend teams on API design - Experience delivering apps in banking, insurance, fintech or healthcare, including PII handling and regulatory constraints (PSD2 / SCA, GDPR) - Clear communication with non-engineers: you explain trade-offs to a product owner and estimate honestly - Full professional fluency in Polish and English - Nice to have: - Mobile payments integration (Apple Pay, Google Pay, BLIK) - Accessibility auditing experience (VoiceOver, TalkBack) - Tech lead or team lead experience on a client-facing engagement - Building your team's AI tooling: custom agents, MCP servers or codebase-specific skills and prompts - Shipping an SDUI-based app at scale, or contributing to an open-source SDUI framework Benefits - Real ownership of the apps you build and direct contact with client product owners — no ten-layer review pyramid - Competitive compensation on B2B contract - Annual training and certification budget - Remote work model with access to a central Warsaw office - A seat at the table in shaping a young firm: our mobile practice, engineering standards, hiring and culture