Senior KMP Engineer (Mobile & Backend)

Integral Solutions - Data & AI; Województwo mazowieckie; Remote; PLN 341,000 - 366,000; Part time

Job summary

Integral Solutions - Data & AI is seeking a Senior KMP Engineer to work remotely from Poland on a mobile and backend role. The stack includes Kotlin, Kotlin Multiplatform, Java, and Spring Boot, with cloud services and CI/CD involved.

You will own features end-to-end from design to production support and help shape the mobile platform strategy. The role emphasizes end-to-end ownership, collaboration with cross-functional teams, and building scalable, secure, real-time financial platform

Qualifications

• Experience in mobile app development with Kotlin or Kotlin Multiplatform.
• Strong knowledge of Android/iOS architectures and software design principles.
• Backend experience with Java, Spring Boot, APIs, and microservices.
• Familiarity with distributed systems, event-driven architectures, and modern engineering practices.
• Experience with CI/CD, automated testing, and production environments.

Responsibilities

• Develop shared business logic across mobile platforms using Kotlin Multiplatform (KMP).
• Design and build backend services and APIs using Java, Kotlin, and Spring Boot.
• Build and enhance customer-facing mobile features used by real customers every day.
• Work with cloud services, CI/CD, observability, monitoring, and production systems.
• Improve scalability, reliability, performance, security, and user experience.
• Collaborate closely with product, design, architecture, security, and platform teams.
• Drive engineering excellence through technical leadership, mentoring and best practices.

Skills

Kotlin

Kotlin Multiplatform

Mobile development

CI/CD

Tools

Spring Boot

Java

Job description

Job title: Senior KMP Engineer (Mobile & Backend)

Location: Remote anywhere from Poland

Work mode: Remote

Type of cooperation: B2B contract

Salary range: B2B: 7000 - 7500 Euro/month - netto

About The Company/project

Build the Next Generation of Digital Financial Products Join a team building one of the largest digital financial platforms in its market, serving millions of customers and processing millions of real-time financial transactions every month.

This is a unique opportunity to work on products that have become a natural part of users' daily lives, delivering fast, secure, and seamless financial experiences at scale. As a Senior KMP Engineer, you will contribute across the entire technology stack - from customer-facing mobile applications and shared cross-platform logic to backend services, APIs, cloud infrastructure, and large-scale production systems.

Our core technology stack includes Kotlin, Kotlin Multiplatform (KMP), Java, and Spring Boot.

Why Join Us?

• Build products used daily by millions of customers.
• Work on large-scale, business-critical systems processing millions of real-time financial transactions every month.
• Take full end-to-end ownership of features, from design and implementation to deployment and production support.
• Help shape the future of our mobile platform strategy through Kotlin Multiplatform (KMP).
• Collaborate in small, high-impact teams where engineers have real influence on technical decisions.
• Solve challenging problems across mobile development, backend services, cloud infrastructure, scalability, reliability, and security.
• Be part of an engineering culture where AI is used every day as a practical development tool, accelerating delivery and enabling engineers to focus on solving meaningful business and technical challenges.

Responsibilities

• What You’ll Do
  • Develop shared business logic across mobile platforms using Kotlin Multiplatform (KMP).
  • Design and build backend services and APIs using Java, Kotlin, and Spring Boot.
  • Build and enhance customer-facing mobile features used by real customers every day.
  • Work with cloud services, CI/CD, observability, monitoring, and production systems.
  • Improve scalability, reliability, performance, security, and user experience.
  • Collaborate closely with product, design, architecture, security, and platform teams.
  • Drive engineering excellence through technical leadership, mentoring and best practices.

You Are An Ideal Candidate If You Have

What We're Looking For

• Strong commercial experience in mobile application development with Kotlin or Kotlin Multiplatform.
• Deep understanding of modern Android OR iOS architectures and software design principles.
• Strong Kotlin skills and experience building high-quality, production-grade applications.
• Some backend development experience with Java, Spring Boot, APIs, and microservices - Big Advantage
• Familiarity with distributed systems, event-driven architectures, and modern engineering practices.
• Experience with CI/CD, automated testing, and production environments.
• Ability to take end-to-end ownership of features from design through production.
• Strong communication and collaboration skills.

Nice To Have

• Experience in fintech, banking, payments, or other regulated industries.
• Experience with Apple Pay, Google Pay, wallet technologies, or payment integrations.
• Experience building modular mobile applications, SDKs, or shared libraries.
• Experience with observability, performance optimization, and production incident analysis.