Senior Full Stack Mobile Developer

N-iX; Poland; Hybrid; PLN 180,000 - 300,000; Full time

Benefits offered by this job

Flexible work formats

Competitive salary and package

Mentorship program and tech trainings

Active tech communities and knowledge‑

Job summary

N-iX is seeking a Senior Full Stack Mobile Developer to join our Clint`s team. You’ll build modern mobile products end‑to‑end, from the mobile app to backend services, APIs, and cloud solutions, writing clean code and embracing AI tools to accelerate development.

You’ll work across mobile apps, shared logic, backend services and production systems, mentoring peers and helping define engineering practices. A strong emphasis on performance, security and maintainability is expected.

Qualifications

• Strong experience in mobile application development.
• Deep understanding of iOS & Android Architecture Components.
• Strong Kotlin skills and modern mobile architecture.
• Backend development experience with Java 7+ and Spring Boot.

Responsibilities

• Build and improve mobile features used by real customers.
• Develop shared business logic for mobile platforms, mainly using Kotlin Multiplatform (KMP).
• Build backend services and APIs using Java/Kotlin and Spring Boot.
• Work with cloud services, CI/CD pipelines, monitoring and production support.
• Improve performance, reliability, security and user experience.
• Use AI coding tools to help with development, testing, documentation and troubleshooting.
• Work closely with product, design, architecture, security and platform teams.
• Help define good engineering practices and mentor other developers.

Skills

Mobile development

Kotlin

Kotlin Multiplatform

Java

Spring Boot

REST API

Microservices

Kafka

AWS

CI/CD

AI tools

Code quality

Tools

Flutter

React Native

GitHub Copilot

Cursor

Claude Code

Gemini Code Assist

Job description

N-iX is a global technology company that helps industry-leading companies and Fortune 500 firms build software products and scalable engineering solutions. Since 2002, we’ve become a team of 2,400+ tech professionals working across 40+ countries worldwide, now actively growing in LATAM. With our office in Medellín and a 100+ strong tech community in the region, we offer flexible work options, global collaboration, room to grow, and opportunities to contribute to meaningful global project

Currently, we are looking for a Senior Full Stack Mobile Developer to join our Clint`s team. The expert who can build modern mobile products end-to-end: from the mobile app experience to backend services, APIs, cloud services and production quality. This role is for someone who enjoys solving real product problems, writing clean code, learning new technologies and using AI tools to work faster and better.

You will join a team building next-generation digital financial products used by customers at scale. You will work across the mobile app, shared mobile logic, backend services and production systems.

What you will do:

• Build and improve mobile features used by real customers.
• Develop shared business logic for mobile platforms, mainly using Kotlin Multiplatform (KMP).
• Build backend services and APIs using Java/Kotlin and Spring Boot.
• Work with cloud services, CI/CD pipelines, monitoring and production support.
• Improve performance, reliability, security and user experience.
• Use AI coding tools to help with development, testing, documentation and troubleshooting.
• Work closely with product, design, architecture, security and platform teams.
• Help define good engineering practices and mentor other developers.

What we are looking for

• We are looking for a strong engineer, not just a person who knows one framework. KMP experience is a strong advantage, but it is not the only path into this role.
• Strong experience in mobile application development.
• Deep understanding of iOS & Android Architecture Components.
• Strong Kotlin skills and good understanding of modern mobile architecture.
• Experience building production-grade apps with good quality, performance and maintainability.
• Backend development experience with Java 7+ and Spring Boot.
• Understanding of APIs, microservices and event-driven systems.
• Experience with CI/CD, automated testing and production systems.
• Ability to take ownership of a feature from design to production.
• Good communication skills and ability to work with multiple teams.

Cross-platform experience

• Our strategic direction is Kotlin Multiplatform, because it lets us reuse business logic while still keeping native-quality mobile experiences. However, we also welcome candidates with strong experience in other cross-platform technologies.
• Kotlin Multiplatform (KMP) experience is preferred.
• Flutter experience is relevant, especially if you worked on architecture, shared logic and production apps.
• React Native experience is relevant, especially if you worked on platform integration and complex mobile products.
• If you are strong in Flutter or React Native and willing to learn KMP, we want to talk to you.

Backend and cloud experience

• Java 7+ and/or Kotlin backend development.
• Spring Boot and REST/API development.
• Microservices and distributed systems.
• Kafka or other event-based technologies.
• Cloud services, preferably AWS.
• High-scale or high-availability production systems.
• We believe modern software development combines strong engineering fundamentals with the effective use of AI and automation.
• As part of our engineering culture, we follow a Specification-Driven Development (SDD) approach, where clear requirements, technical designs, examples, and tests are used to drive implementation and ensure high-quality outcomes.
• Use AI coding assistants such as GitHub Copilot, Cursor, Claude Code, Gemini Code Assist or similar tools.
• Use AI to help with code generation, unit tests, documentation, refactoring and debugging.
• Critically review AI-generated output and maintain high standards for code quality, security, performance, and maintainability.
• Be open to working with AI agents as part of the development lifecycle.

Nice to have

• Experience in fintech, banking, payments or other regulated environments.
• Experience with Apple Pay, Google Pay or wallet/payment integrations.
• Experience building modular mobile apps or shared SDKs/libraries.
• Experience with observability, performance profiling and production incident analysis.

Who will succeed in this role?

• A developer who can learn fast and is not afraid of new technologies.
• Someone who understands both product experience and system design.
• A person who can work independently but also collaborate well with others.
• An engineer who cares about clean code, reliability, security and customers.
• Someone who wants to be part of the next generation of AI-empowered full stack development.

In simple terms: we are looking for a strong mobile-first full stack developer who can build customer-facing apps, connect them to strong backend services, learn KMP if needed, and use AI tools as part of a modern development workflow.

We offer*:

• Flexible working format - remote, office-based or flexible
• A competitive salary and good compensation package
• Professional development tools (mentorship program, tech talks and trainings, centers of excellence, and more)
• Active tech communities with regular knowledge sharing