Hi, I’m Koray Metin, a Flutter Engineer with 5+ years of direct Flutter experience and a strong native iOS background. I specialize in building scalable, offline-first mobile apps using Flutter, Clean Architecture and BLoC/Cubit. I focus on performance optimization, maintainable architectures and testable codebases. I’ve led migrations, built modular architectures, integrated BLE, API-driven systems, and localization for multi-market rollouts. I’m passionate about delivering robust, maintainable code and collaborating across teams to ship high-quality mobile experiences.…

Koray Metin

Hi, I’m Koray Metin, a Flutter Engineer with 5+ years of direct Flutter experience and a strong native iOS background. I specialize in building scalable, offline-first mobile apps using Flutter, Clean Architecture and BLoC/Cubit. I focus on performance optimization, maintainable architectures and testable codebases. I’ve led migrations, built modular architectures, integrated BLE, API-driven systems, and localization for multi-market rollouts. I’m passionate about delivering robust, maintainable code and collaborating across teams to ship high-quality mobile experiences.…

Available to hire

Hi, I’m Koray Metin, a Flutter Engineer with 5+ years of direct Flutter experience and a strong native iOS background. I specialize in building scalable, offline-first mobile apps using Flutter, Clean Architecture and BLoC/Cubit. I focus on performance optimization, maintainable architectures and testable codebases.

I’ve led migrations, built modular architectures, integrated BLE, API-driven systems, and localization for multi-market rollouts. I’m passionate about delivering robust, maintainable code and collaborating across teams to ship high-quality mobile experiences.

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Skills

Experience Level

Flutter
Expert
Dart
Expert
Swift
Expert
API
Expert
Objective-C
Expert
SQLite
Expert

Language

English
Advanced
Turkish
Fluent

Work Experience

Flutter Developer (Contract) at Cuisine Barista AG (via Buluter GmbH)
January 1, 2026 - Present
Contract Flutter developer building a companion mobile app for a connected coffee machine. I delivered a single codebase for iOS and Android, designed a customer coffee profile flow with three brewing parameters (grind, temperature, volume), and enabled users to create, save, and sync personalized recipes to the machine. I integrated the vendor BLE SDK on the app side, handling pairing, connection state, error recovery, and providing clear feedback during customer sync. I implemented full localization across 10+ languages to support rollout across European markets.
Senior Flutter Developer at Ximmio BV
January 1, 2023 - December 1, 2025
Led a 2.5-year rewrite of Vehicle App — the company's flagship native Android product — into Flutter with a modular architecture of 16 feature modules. Architected offline-first mode with MapsForge offline maps and SignalR real-time server sync, now used by 300+ vehicles to complete routes. Rebuilt route optimization and introduced targeted unit test coverage on critical database and routing paths, addressing longstanding issues from the native Android version. Shipped Vehicle App on Flutter; within 6 months of release, 5 new customers adopted it as their primary navigation system for daily waste collection operations. Integrated AI coding tools over 1.5 years, accelerating development and geographic calculations.
Flutter Developer at Ximmio BV
October 1, 2019 - December 1, 2022
Led the pilot migration of a customer's native iOS app to Flutter in 5 months, rebuilding 70% of the core library's functionality while mentoring one junior developer through the rewrite. Led a mobile team of 2 engineers for 1 year, driving Flutter rollout across remaining customer apps in the platform. Migrated all 14 customer apps from native iOS to Flutter in 2 years, while onboarding 4 new customers to the Flutter platform.
iOS Developer at Ximmio BV
January 1, 2016 - October 1, 2019
Built the core iOS modular library from an empty project, configured via JSON for UI, modules and per-customer setup, powering white-label waste management apps across Netherlands municipalities. Rebuilt the library in Swift over 8 months from Objective-C, then migrated all deployed customer apps to the new architecture, improving maintainability and feature velocity. Scaled the platform from 5 to 14 customer apps through migration and modular architecture enabling onboarding with minimal code changes.
iOS Developer at Manggis Information Systems
September 1, 2012 - December 31, 2015
Built and shipped 20+ native iOS applications in Objective-C across social, university and location-based categories. Owned the App Store release pipeline, handling provisioning, code signing, App Store Connect submissions and TestFlight beta distribution to internal testers.

Education

Bachelor's Degree in Computer Engineering at Cukurova University
January 1, 2008 - January 1, 2012
Bachelor's Degree in Computer Engineering at Cukurova University
January 1, 2008 - January 1, 2012

Qualifications

Add your qualifications or awards here.

Industry Experience

Software & Internet, Media & Entertainment, Professional Services
    WasteDrop (smart waste containers) | Flutter

    A consumer app to open underground waste containers with a phone. Users find containers on a map, top up their account balance, pay per drop, and manage their account. Available in Belgium

    • WasteDrop (10,000+ per platform)
    iOS: https://www.twine.net/signin
    Android: https://www.twine.net/signin

    Vehicle Ximmio (fleet navigation app) | Flutter

    A Flutter fleet app for waste collection drivers in the field. Drivers receive work orders, follow collection routes with GPS, complete tasks with photos and notes, and manage digital waybills. Includes offline support, so drivers can keep working in areas with no mobile coverage.

    Downloads / users: 300+ vehicles; 5 new B2B customers within 6 months of release
    Currently live: Yes
    Note: B2B/internal project (not in public app stores). Screenshots are on my portfolio: https://www.twine.net/signin
    com