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Sinan Koyuncu

@sinankoyuncu

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Senior iOS developer specializing in Swift, app architecture, and performance.

Turkey

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What I'm looking for

I seek roles where I can lead native iOS development, mentor teams, drive architecture and performance improvements, and apply emerging AI workflows within agile product-focused companies.

I am a Senior iOS Developer with over 10 years of experience building scalable, high-performance mobile applications for enterprises and startups. I specialize in Swift and native iOS development, have led migrations from Objective-C and Flutter to native iOS, and consistently drive improvements in app performance and user experience.

I architect and implement production-ready solutions, mentor junior engineers, and collaborate closely with design, product, and backend teams in Agile environments. My work has included building reference architectures adopted across portfolios, reducing crash rates, and implementing CI/CD and performance monitoring to ensure app health.

I am enthusiastic about AI and agentic workflows and actively developing skills to apply them to future products. I bring a pragmatic, quality-focused approach to mobile engineering with strong experience across SwiftUI, Combine, RxSwift, Flutter, and modern architectures like VIPER and MVVM.

Experience

Work history, roles, and key accomplishments

Current

Mobile / AI Developer

Current

Youna

Jan 2026 - Present (9 months)

Built and launched Youna, an AI-powered wellbeing and journaling product, leading the full lifecycle from product design and architecture to development, monetization, and App Store launch. Designed multi-stage AI workflows with LangGraph and built a long-term contextual memory architecture using RAG and vector retrieval.

Swift SwiftUI LangGraph RAG Vector Databases Firebase app store AI Workflows Contextual Memory

Current

Senior iOS Developer

Current

Machinarium

Dec 2024 - Present (1 year 10 months)

Led migration of a global-scale e-commerce app from Flutter to native iOS, improving performance and user experience; added native features and supported international user growth in Agile releases.

Swift SwiftUI Performance Profiling Debugging Agile CI CD App Store Connect VIPER iOS Flutter Cross Functional Collaboration

Senior iOS Developer

Yildiz Tech

Sep 2022 - Nov 2024 (2 years 2 months)

Architected and implemented an online marketing app for Şok Market adopted as a reference architecture; partnered with design and backend teams to deliver scalable, high-performing solutions for large retail user bases.

Swift MVVM Architecture Performance Monitoring Scalability Cross Functional Collaboration Testing iOS Code Quality Agile

Senior iOS Developer

Boyner Group

Jul 2021 - Aug 2022 (1 year 1 month)

Migrated a large Objective-C e-commerce app to Swift, implemented features that increased customer engagement and app ratings, and coached junior developers while improving Agile processes.

Swift Objective C Migration Performance Profiling Coaching Agile Debugging iOS

Senior iOS Developer

MagClick

Sep 2020 - Jul 2021 (10 months)

Developed Opet's customer loyalty app and contributed to large-scale financial app fixes; implemented features using VIPER and introduced CI/CD pipelines to improve release frequency.

Swift VIPER CI CD Agile Debugging Testing Release Management

Senior iOS Developer

Magiclick

Sep 2020 - Jul 2021 (10 months)

Developed Opet's customer loyalty app, coordinating with product, design, and QA teams to deliver new features and enhancements. Designed and implemented features using VIPER architecture and implemented CI/CD pipelines.

iOS Swift VIPER CI CD Agile Debugging

iOS Developer

Dijital Sahne

Apr 2018 - Sep 2020 (2 years 5 months)

Improved performance and stability of a business management app, reducing crash rates by 40%; delivered multiple Flutter apps and mentored developers to accelerate Flutter adoption.

Swift Flutter Dart Performance Optimization Mentorship Cross Platform Development Firebase CI CD

iOS / Flutter Developer

Dijital Sahne

Apr 2018 - Sep 2020 (2 years 5 months)

Improved performance and stability of a client-facing business management app by identifying and resolving critical bottlenecks, reducing crash rates by 40%. Delivered multiple Flutter apps to market as an early adopter of cross-platform development.

iOS Flutter Performance Optimization Cross Platform Development

iOS Developer

Piblo

May 2016 - Apr 2018 (1 year 11 months)

Built and launched two iOS apps from scratch in a startup environment, integrated cloud services and modern architectural patterns to improve reliability and scalability.

Swift IOS SDK API Integration App Store Deployment MVC MVVM Cloud Services iOS App Development Product Strategy

iOS/Android Developer

Dijital Sahne

Jun 2015 - May 2016 (11 months)

Designed, developed, and published iOS and Android versions of a newspaper app end-to-end, managing full lifecycle from coding to App Store and Google Play release.

iOS Android App Store Deployment Cross Platform Development Testing Release Management Mobile Development app store Google Play

Intern Programmer

Argela

Aug 2013 - May 2016 (2 years 9 months)

Contributed to an international telecommunications project.

Telecommunications Programming

Software Developer

Makrosum

Sep 2014 - May 2015 (8 months)

Edited and developed e-commerce package applications and created new packages in collaboration with senior developers, gaining experience across core programming tasks and deployment.

Software Development PHP Testing Collaboration Web Development Ecommerce

Intern Programmer

Argela Technologies

Aug 2013 - Sep 2013 (1 month)

Worked with senior developers on a project for an international telecommunications client, reviewed code, and produced bug-fix reports to support delivery quality.

Code Review Bug Reporting Telecommunications Collaboration Software Testing Documentation