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Senior Flutter developer with 7+ years of experience building fast, scalable, and user-friendly mobile applications for Android and iOS. I specialize in enterprise-grade solutions, cross-platform hardware/payment integrations, and reliable release processes. I’ve led complex integrations (e.g., Tap-on-Mobile POS via custom Android channels and intent-based flows), comprehensive localization migrations (gen-l10n) across 8+ languages, and real-time WebSocket chat systems. I also improve quality via testing, refactoring, and CI/CD optimization, while actively incorporating AI-powered tooling into my daily workflow.…Senior Flutter developer with 7+ years of experience building fast, scalable, and user-friendly mobile applications for Android and iOS. I specialize in enterprise-grade solutions, cross-platform hardware/payment integrations, and reliable release processes. I’ve led complex integrations (e.g., Tap-on-Mobile POS via custom Android channels and intent-based flows), comprehensive localization migrations (gen-l10n) across 8+ languages, and real-time WebSocket chat systems. I also improve quality via testing, refactoring, and CI/CD optimization, while actively incorporating AI-powered tooling into my daily workflow.

Emil Zając

App Developer, Web Developer, Back-End Developer

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Senior Flutter developer with 7+ years of experience building fast, scalable, and user-friendly mobile applications for Android and iOS. I specialize in enterprise-grade solutions, cross-platform hardware/payment integrations, and reliable release processes. I’ve led complex integrations (e.g., Tap-on-Mobile POS via custom Android channels and intent-based flows), comprehensive localization migrations (gen-l10n) across 8+ languages, and real-time WebSocket chat systems. I also improve quality via testing, refactoring, and CI/CD optimization, while actively incorporating AI-powered tooling into my daily workflow.…Senior Flutter developer with 7+ years of experience building fast, scalable, and user-friendly mobile applications for Android and iOS. I specialize in enterprise-grade solutions, cross-platform hardware/payment integrations, and reliable release processes. I’ve led complex integrations (e.g., Tap-on-Mobile POS via custom Android channels and intent-based flows), comprehensive localization migrations (gen-l10n) across 8+ languages, and real-time WebSocket chat systems. I also improve quality via testing, refactoring, and CI/CD optimization, while actively incorporating AI-powered tooling into my daily workflow.

Available to hire

Senior Flutter developer with 7+ years of experience building fast, scalable, and user-friendly mobile applications for Android and iOS. I specialize in enterprise-grade solutions, cross-platform hardware/payment integrations, and reliable release processes.

I’ve led complex integrations (e.g., Tap-on-Mobile POS via custom Android channels and intent-based flows), comprehensive localization migrations (gen-l10n) across 8+ languages, and real-time WebSocket chat systems. I also improve quality via testing, refactoring, and CI/CD optimization, while actively incorporating AI-powered tooling into my daily workflow.

Skills

Experience Level

Expert

Expert

Expert

Expert

Expert

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Expert

Expert

Expert

Intermediate

Language

Work Experience

Senior Flutter Developer at Smartive.app

June 1, 2025 - Present

Built and maintained production-grade Flutter mobile applications for Android and iOS in live environments. Delivered and supported payment gateway and Soft POS integrations, including Viva Wallet, Worldline, and Zen payment flows. Supported payment-related operational processes across multiple markets with country-specific adaptations. Implemented SEO strategies to improve organic traffic and search rankings. Enhanced inventory management systems, reducing costs by 15% and improving operational efficiency. Launched targeted marketing campaigns to increase brand awareness and conversions.

Flutter Developer at Goelett (Business Travel App)

April 1, 2023 - June 1, 2025

Led development of key features that contributed to a 250% increase in user adoption. Refactored the app for improved code quality, performance, and long-term maintainability, resulting in improved test coverage from 24% to 85%. Proposed and implemented technical solutions with better performance and reduced maintenance costs. Performed deep code reviews, participated in Scrum meetings, and mentored junior developers in Flutter best practices.

Co-Founder at Twin Flames Jewelry

May 1, 2022 - Present

Developed and optimized an e-commerce website, improving Google Speed Insights scores to 90%+ on mobile, resulting in faster load times and improved customer experience.

Flutter Developer at Online-Tribes

August 1, 2021 - April 1, 2023

Collaborated with the project team to proactively resolve issues and ensure smooth progress and timely delivery. Optimized Firebase data management, improving data retrieval efficiency by 30%. Increased user satisfaction via UX improvements and mobile app optimizations. Wrote unit and integration tests, increasing test coverage from 60% to 85% and reducing technical debt.

Freelance Flutter Developer at Upwork

August 1, 2019 - October 1, 2022

Delivered high-quality mobile applications meeting client specifications and deadlines. Tested applications and fixed bugs before feature implementation to improve user experience and deliver reliable outcomes. Troubleshot client apps, optimized functionality, and reduced reported issues by 20%. Managed Android app lifecycle to ensure timely releases and long-term client relationships.