Fullstack Mobile Developer ( Kotlin)

Integral Solutions - Data & AI; Warszawa; Hybrid; PLN 316,000 - 365,000; Full time

Job summary

Integral Solutions - Data & AI is seeking a Fullstack Mobile Developer (Kotlin Multiplatform) to build features for fintech mobile apps, focusing on cross-platform logic and native experiences.

You will work remotely and in a hybrid setup with product, design, architecture, security and platform teams. Hands-on, fast-learning and collaborative, you’ll enhance backend services and production systems using Java/Kotlin and Spring Boot.

Qualifications

• Strong experience in mobile app development, with cross-platform knowledge.
• Deep understanding of iOS and Android Architecture Components.
• Strong Kotlin skills and modern mobile architecture experience.
• Backend development with Java and Spring Boot.
• Experience with APIs, microservices and event-driven systems.
• CI/CD, automated testing and production systems experience.
• Ability to own a feature from design to production.
• Good communication across multiple teams.

Responsibilities

• Build and improve mobile features used by real customers.
• Develop shared business logic for mobile platforms using Kotlin Multiplatform.
• Build backend services and APIs with 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 assist development, testing and documentation.
• Collaborate with product, design, architecture, security and platform teams.
• Help define engineering practices and mentor developers.

Skills

Mobile development

Kotlin

Kotlin Multiplatform

Java

Spring Boot

APIs / Microservices

CI/CD

Ownership

Tools

Kotlin Multiplatform

Spring Boot

Java

CI/CD tools

Job description

Job title: Fullstack Mobile Developer (Kotlin Multiplatform)

Location: Poland / Remote/ Warsaw

Work mode: Remote/ Hybrid

Type of cooperation: B2B contract

Salary range: B2B 6500 - 7500 Euro/month- netto

About The Company/project

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.

We are moving towards a new development model: smaller teams with stronger ownership, more code reuse between platforms, and practical use of AI development tools. You do not need to know everything on day one, but you should be curious, hands-on and able to learn quickly.

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.

You Are An Ideal Candidate If You Have

• 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 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.

Nice To Have

• Strong communication and teamwork skills
• Ability to thrive in a fast-paced, dynamic environment
• Proactive, "Can-Do" attitude
• Strong problem-solving and system-thinking abilities