Flutter Developer

X-FLOW; Warszawa; Hybrid; PLN 180,000 - 270,000; Full time

Benefits offered by this job

Competitive salary

Flexible hours

Remote/office mix

Career growth

Creative culture

Job summary

X-FLOW in Warsaw is seeking a senior Flutter Developer to join the flagship Happy Color project and new ventures. You will build high-quality Flutter apps, implement adaptive UI and smooth animations, and design modular architectures for both iOS and Android.

Collaborate with designers and backend engineers, optimize performance, and contribute to automated tests. The role offers flexible hours and remote/office options with a creative, inclusive culture.

Qualifications

• 4+ years of Flutter/Dart experience.
• Solid understanding of widget lifecycle, state management, and animation system.
• Strong knowledge of Flutter SDK (animations, adaptive UI, rendering, performance tuning).
• Proficiency in Dart (async programming, isolates, generics, mixins).
• Experience building custom UI components, pixel-perfect layouts, and smooth 60/120 FPS animations.

Responsibilities

• Develop and maintain high-quality Flutter applications with a focus on performance, stability, and clean architecture.
• Implement adaptive, responsive UI and complex animations with pixel-perfect precision.
• Design modular and testable architectures.
• Identify and fix performance bottlenecks (scrolling, rendering, rebuilds).
• Collaborate with designers and backend engineers to deliver smooth UX across iOS and Android.
• Improve code quality through reviews, refactoring, and automated testing.

Skills

Flutter/Dart

Animations

Responsive UI

Unit & integration tests

Firebase integration

Tools

Flutter DevTools

Bloc/Cubit/Provider

Job description

X-FLOW is a mobile game development company established in 2018. We gained recognition after the release of Happy Color, the most popular digital coloring book and one of the most successful ad-driven mobile apps in the world.

We are looking for a Flutter Developer for our flagship project, Happy Color, and for development of new projects.

Key Responsibilities:

• Develop and maintain high-quality Flutter applications with a focus on performance, stability, and clean architecture.
• Implement adaptive, responsive UI and complex animations with pixel-perfect precision.
• Design modular and testable architectures.
• Identify and fix performance bottlenecks (scrolling, rendering, rebuilds).
• Collaborate closely with designers and backend engineers to deliver smooth UX across iOS and Android.
• Continuously improve code quality through reviews, refactoring, and automated testing.

Requirements:

• 4+ years of Flutter/Dart experience with solid understanding of widget lifecycle, state management, and animation system.
• Strong knowledge of Flutter SDK (animations, adaptive UI, rendering, performance tuning).
• Proficiency in Dart (async programming, isolates, generics, mixins).
• Experience building custom UI components, pixel-perfect layouts, and smooth 60/120 FPS animations.
• Deep understanding of Bloc / Cubit / Provider and clean architectural principles (SOLID, Clean Architecture).
• Hands-on experience with Flutter DevTools for performance profiling and optimization (scroll, rebuilds, memory).
• Ability to integrate Firebase, analytics, in-app purchases, and push notifications.
• Understanding of Android/iOS ecosystems and platform channels for native integrations.
• Experience writing and maintaining unit and integration tests.

What We Offer:

• Competitive salary and benefits package.
• Opportunity to work with a talented and passionate team in a creative and dynamic environment.
• Flexible working hours and remote/office work options.
• Career growth and professional development opportunities.
• A fun and inclusive company culture that celebrates diversity and creativity.

Join us and let’s create great content together!