Senior Kotlin Multiplatform Engineer

N-iX; Madrid; A distancia; EUR 55.000 - 75.000; Jornada completa

Descripción de la vacante

A leading technology company in Madrid is seeking an experienced mobile application developer specializing in Kotlin Multiplatform. You will be responsible for developing high-performance applications for iOS and Android, ensuring optimal performance and user experience. The ideal candidate has at least 6 years of experience and strong skills in Kotlin and agile methodologies. This role offers a competitive salary and flexible working arrangements.

Servicios

Flexible working format

Competitive salary and good compensation package

Personalized career growth

Professional development tools

Active tech communities

Education reimbursement

Corporate events and team buildings

Formación

• 6 years of experience in mobile application development.
• At least 2 years of hands-on experience with Kotlin Multiplatform (KMP).
• Deep expertise in Kotlin, including coroutines and shared data management.
• Strong understanding of platform interoperability between Kotlin and Swift.
• Experience with CI/CD for mobile applications.

Responsabilidades

• Develop high-performance mobile applications for iOS and Android.
• Design and implement shared business logic and platform-specific layers.
• Architect applications using Clean Architecture / MVVM / MVI.
• Optimize application performance and memory management.
• Implement automated build and release pipelines.

Conocimientos

Kotlin Multiplatform (KMP)

Mobile application development

Bluetooth / BLE

Agile development

English proficiency

Performance optimization

Herramientas

GitHub Actions

Bitrise

Fastlane

Ktor Client

Retrofit

Descripción del empleo

About the Client :

Our customer is a leading provider of onboard retail technology and mobile solutions for the travel and retail industries. The company designs and builds digital products that transform how airlines trains and retailers manage in-motion sales inventory and customer experiences.

We are forming a dedicated Kotlin Multiplatform (KMP) team to build a new cross-platform mobile application from the ground up one codebase two native experiences: iOS and Android. You’ll join a small highly skilled Scrum team that owns the full delivery pipeline from architecture and development to testing optimization and release.

Responsibilities :

• End-to-end development of high-performance mobile applications for both iOS and Android using Kotlin Multiplatform (KMP).
• Design and implement shared business logic and platform-specific layers to ensure native user experience and optimal performance on each platform.
• Architect the application using Clean Architecture / MVVM / MVI ensuring modularity scalability and maintainability.
• Experience with device-to-device communication protocols especially Bluetooth / BLE.
• Develop rich responsive UI layers using Jetpack Compose (Android) and SwiftUI (iOS) where necessary leveraging Compose Multiplatform when appropriate.
• Integrate with backend APIs (REST / GraphQL) manage data synchronization caching and offline capabilities.
• Optimize app performance memory usage and responsiveness for both platforms.
• Implement comprehensive testing: unit integration and UI tests across platforms.
• Configure and maintain automated build test and release pipelines (CI / CD) for Android and iOS using tools like GitHub Actions Bitrise or Fastlane.
• Participate in code reviews technical discussions and agile ceremonies ensuring continuous improvement and delivery excellence.
• Collaborate closely with backend engineers designers and QA to deliver polished high-quality user experiences.

Must-Have Skills :

• 6 years of experience in mobile application development.
• At least 23 years of proven hands‑on experience delivering production apps using Kotlin Multiplatform (KMP) for both Android and iOS.
• Deep expertise in Kotlin including coroutines flows multiplatform libraries and shared data management.
• Experience with Bluetooth / BLE.
• Strong understanding of platform interoperability bridging shared Kotlin code with Swift / SwiftUI on iOS and Jetpack Compose on Android.
• Experience developing and optimizing native UI components for each platform.
• Solid understanding of mobile performance optimization (memory management rendering startup time network performance).
• Experience integrating RESTful APIs or GraphQL using Ktor Client or Retrofit with offline caching (SQLDelight / Room).
• Experience with CI / CD for mobile (Bitrise GitHub Actions Fastlane Jenkins) and mobile release processes (Google Play App Store).
• Strong Git workflow and experience with agile development environments (Scrum / Kanban).
• Fluent in English both spoken and written.
• Clear communication skills: being able to explain complex technical issues to non‑technical stakeholders.
• Experience in offline‑first architectures synchronization logic and push notifications.

Would be a plus :

• Experience of mesh networking protocols and device‑to‑device communication.

We offer

• Flexible working format - remote office-based or flexible
• A competitive salary and good compensation package
• Personalized career growth
• Professional development tools (mentorship program tech talks and trainings centers of excellence and more)
• Active tech communities with regular knowledge sharing
• Education reimbursement
• Memorable anniversary presents
• Corporate events and team buildings
• Other location‑specific benefits
• not applicable for freelancers

Employment Type :

Full Time

Experience :

years

Vacancy :

1