IT & Software

Mobile Engineer

Hydrogen UK Ltd

London · England · United Kingdom

My client has a need for an experienced Android Engineer to join their team for an initial 8 week piece of work with potential to extend. This is a hybrid role and is outside of IR35

Android (primary depth)

  • Kotlin and modern Android in large production codebases; Jetpack Compose alongside legacy View-based UI
  • Multi-module builds: reading, untangling and mapping them, including convention plugins and version catalogues
  • DI frameworks and the ability to derive actual runtime structure from wiring
  • Architectural patterns in practice (MVVM, MVI, Clean-style layering), and the ability to identify what a codebase genuinely does

Code archaeology and analysis

  • Navigating an unfamiliar large codebase quickly and systematically
  • Static analysis, dependency graph extraction, module dependency visualisation, code search at scale
  • Reading CI/CD pipelines as a source of architectural truth: Fastlane, Bitrise, GitHub Actions, Jenkins, Gradle/Xcode build logic
  • Reconstructing runtime behaviour from instrumentation, logging and observability tooling (Crashlytics, Sentry, Dynatrace, Firebase or similar)

Backend and API

  • Tracing a request from UI through the mobile networking layer to the backend service and back
  • REST/GraphQL/gRPC, OpenAPI and contract inspection, API gateway and BFF patterns
  • OAuth 2.0 / OIDC token flows as implemented on device
  • Third-party SDK inventory and assessment: analytics, payments, chat, fraud, marketing, feature flags

Banking-specific mobile concerns

  • Secure storage, biometric authentication, device binding, certificate pinning as implemented in code
  • Feature flags, remote config, phased/staged rollout, kill switches
  • Offline behaviour, caching and state management, and what happens at the edges

Essential non-technical skills

  • Structured interviewing – runs a technical interview that yields specifics rather than a tour of opinions, and captures it in a form the team can use
  • Rigorous note-taking and traceability – findings can be traced back to a source; distinguishes what was observed in code from what someone said
  • Collaborative, non-territorial — will be reviewing other engineers' work in front of them; needs to do it without triggering defensiveness
  • Self-directed under time pressure — 8 weeks means little supervision and no ramp-up period
  • Fluent professional English, spoken and written

Nice to have

  • Financial services or other regulated-sector mobile delivery
  • Kotlin Multiplatform, React Native, or hybrid/webview integration experience
  • Diagramming from code: Structurizr, PlantUML, Mermaid, dependency-graph tooling
  • Accessibility and performance profiling experience
  • Consultancy or contracting background with multiple client environments
  • iOS working knowledge (second depth) - Swift, SwiftUI/UIKit, SPM and Xcode project structure — sufficient to read the codebase and validate the Architect's iOS findings

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Reference: WJ-766_22185615

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