Senior Flutter Developer

Onthespotdev; Warszawa; Hybrid; PLN 180,000 - 240,000; Full time

Job summary

On The Spot is recruiting a Senior Flutter Developer to join their Mobile R&D team in Poland. You will design, build, and test Flutter features for Android and iOS within a multi-brand Flutter codebase, aligning with an Israel-based team and a fast-moving financial environment.

You’ll own features, maintain high-quality code, and collaborate across Product, Design, Backend, and QA to meet business goals. Polish residency required; Sunday-Thursday work alignment with the Israeli team.

Qualifications

• 5+ years of professional software development experience.
• 4+ years of hands-on Flutter development on production applications.

Responsibilities

• Design, develop, test, and maintain Flutter features for Android and iOS.
• Write clean, well-structured, testable code following team architecture and standards.
• Contribute to integrations like real-time market data, charting, analytics, and third-party SDKs.
• Work within the existing multi-flavor / multi-brand build and release process.
• Troubleshoot and fix production issues to keep apps performant and stable.
• Participate in code reviews and write unit, widget, and integration tests.
• Collaborate with Product, Design, Backend, and QA to deliver business objectives.
• Communicate progress and risks clearly in English with a distributed team.

Skills

Flutter development

Dart

Leadership

Ownership

English communication

Autonomy

Cross-functional collaboration

Problem solving

Tools

Flutter

Dart

Android

iOS

REST APIs

WebSocket

GitLab CI

Firebase

ChartIQ

Braze

Mixpanel

Job description

We bring startups and disruptive tech companies to the local market, offering engineers the opportunity to work on innovative, high-impact products. Join us and become a member of their R&D team while we take care of employment, HR support, a benefits package, and an enjoyable work environment.

Finonex is a company building modern mobile trading and financial applications across multiple brands from a shared Flutter codebase. The team focuses on creating accessible, secure, and user-friendly trading experiences powered by cutting-edge technology, supported by 24/7 service.

About the role

We are looking for a strong, hands-on Senior Flutter Developer to join our Mobile R&D team and help build our mobile trading applications.

This is a hands-on engineering role. You'll design and build high-quality features across Android and iOS, working within an established multi-flavor architecture and to a high engineering standard, as part of a team led by our Mobile Team Lead.

The ideal candidate takes strong ownership of their work, writes clean and maintainable code, and thrives in a fast-moving, regulated financial environment.

Please note that candidates for this position are expected to work in alignment with the Israeli team: Sunday-Thursday — work days, Friday-Saturday — days off.

Responsibilities

Software Development

• Design, develop, test, and maintain high-quality features for Android and iOS in Flutter.
• Write clean, well-structured, testable code that follows the team's architecture, patterns, and coding standards.
• Contribute to integrations such as real-time market data, charting, analytics, and third-party financial SDKs.
• Work within the existing multi-flavor / multi-brand build and release process.
• Troubleshoot and fix production issues, and help keep the apps performant and stable.
  

Quality & Testing

• Participate actively in code reviews - both giving and receiving constructive feedback.
• Write unit, widget, and integration tests to keep quality high.
• Contribute to app reliability and observability (crash-free rates, performance).
  
• Collaborate closely with Product, Design, Backend, and QA to deliver business objectives.
• Deliver predictably within sprints, with honest estimation and clear communication of progress and risks.
• Communicate proactively and clearly in English with a distributed, cross-country team.

Requirements

• 5+ years of professional software development experience.
• 4+ years of hands-on Flutter development on production applications (Flutter as a primary, day-to-day skill - not occasional or secondary).
• Strong command of Dart and modern state management (BLoC, Riverpod, and Provider).
• Solid working experience within multi-flavor / multi-environment Flutter apps.
• Working knowledge of native Android and iOS - build configuration and platform-channel / SDK integration.
• Experience with REST APIs and real-time communication (WebSocket or similar).
• Strong ownership, autonomy, and problem-solving skills.
• Excellent written and verbal English — a must (daily communication with the Israel-based team).
• Availability to work Sunday-Thursday, aligned with the Israeli team — a must.

Nice to have

• Experience in fintech, trading, forex/CFD, financial services, or another regulated industry.
• Experience with the Firebase suite (Crashlytics, Remote Config, Performance, Analytics).
• Experience with product analytics / attribution (e.g. Mixpanel, AppsFlyer).
• Experience with charting libraries (e.g. ChartIQ) and engagement SDKs (e.g. Braze).
• Familiarity with FVM, monorepo workflows, and GitLab CI.
• Experience with automated / integration testing and AI-assisted development tools.
• Experience working in distributed / international teams.

Work days note

For this position, candidates are expected to work in alignment with the Israeli team:

• Friday-Saturday: days off

At On The Spot, we’re creating a workplace people would want to stay in:

supportive, well-organized, and fair in terms of conditions and benefits.

We’ll share more about our benefit package during the interviews. In the meantime, you can always check our Glassdoor reviews .

Position is open to candidates in Poland. You need to have a residence permit or another valid document allowing work in Poland. Thank you!