Junior Mobile App Developer (6-Month Contract)

This is a core mobile application development position at the junior level. You will work day-to-day alongside senior developers, product managers and designers - building cross-platform features with Kotlin Multiplatform and Compose Multiplatform, contributing shared business logic and clean, reusable UI components, and helping integrate APIs, local data, authentication and offline-first functionality. You will assist in debugging across Android and iOS builds, write unit tests for shared logic, and participate in code reviews and testing.

You will grow into cross-platform mobile development as an area of practice. That means learning through structured guidance, asking questions early and often, investigating issues thoroughly and explaining your findings clearly - with the expectation that you develop into a full cross-platform mobile developer within the team.

Responsibilities

Assist in developing cross-platform features using Kotlin Multiplatform (KMP) and Compose Multiplatform (CMP).

Build clean, reusable UI components using Jetpack Compose / Compose Multiplatform.

Work on shared business logic in commonMain, while supporting platform-specific implementations in androidMain and iosMain.

Help integrate APIs, local databases, authentication, notifications, and offline-first functionality.

Collaborate with senior developers to design scalable app architecture using patterns such as MVVM, MVI, or clean architecture.

Write maintainable Kotlin code with proper separation between UI, state management, repositories, and platform services.

Support Android-specific features such as permissions, background tasks, notifications, and deep links.

Support iOS integration through Kotlin/Native, Swift interop, and shared framework usage.

Assist in debugging and fixing issues across Android and iOS builds.

Participate in code reviews, testing, and improving code quality.

Write unit tests for shared logic where appropriate.

Keep documentation updated for shared modules, setup steps, and feature behaviour.

Work closely with product, design, QA, and backend teams to deliver reliable mobile features.

Learn and apply modern mobile development practices, including dependency injection, async flows, local persistence, and CI/CD workflows.

This role is not eligible for UK visa sponsorship. Applicants must have the right to work in the UK independently and for the duration of their employment., Basic experience with Kotlin, Jetpack Compose, or Android development.

Familiarity with KMP/CMP project structure.

Understanding of REST APIs, JSON, coroutines, and flows.

Basic knowledge of local databases such as Room, SQLDelight, or similar.

Interest in cross-platform mobile development and willingness to learn iOS build/debugging workflows.

Experience with Git, pull requests, and collaborative development.

Expected Mindset

Willing to learn and ask questions.

Comfortable working step by step with guidance.

Interested in writing clean, simple, testable code.

Able to investigate bugs and explain findings clearly.

Open to feedback during code reviews.

Keen to grow into a full cross-platform mobile developer role.

H2 Cognitive Designs (H2CD) is a health technology company working at the intersection of cognitive science, clinical research, and large-scale digital assessment. We build platforms used to measure cognitive performance across clinical trials, occupational health programmes, and large institutional deployments in the UK and internationally.

Our clients include demanding and security-conscious organisations across healthcare, national institutions, and sectors where the performance and reliability of what we build genuinely matter. Our infrastructure is cloud-native, and our engineering team is distributed, collaborative, highly skilled and highly specialised. We have a rapidly growing portfolio of significant projects, and this role sits at the heart of how we deliver them.