Milan Susnjar
Verified Expert in Engineering
Mobile Engineer and React Native Developer
Banja Luka, Bosnia and Herzegovina
Toptal member since July 30, 2026
Milan is a senior full-stack engineer with 14 years of experience building cross-platform mobile and web apps. His expertise spans React Native, React, TypeScript, and Node.js with PostgreSQL, with a focus on offline-first architecture and release automation. He built and runs an events app end to end, led mobile development of a facility management app used across Central Europe, and delivered TypeScript web products in construction and renewable energy.
Portfolio
Experience
- JavaScript - 14 years
- React - 10 years
- React Native - 10 years
- TypeScript - 8 years
- Node.js - 6 years
- PostgreSQL - 5 years
- NestJS - 5 years
- Expo - 5 years
Preferred Environment
Git, GitHub, Claude Code
The most amazing...
...app I've shipped is an Expo app I designed, built and run in production, from its data pipeline and API to App Store and Google Play releases.
Work Experience
Senior Software Engineer
ABS Safety GmbH
- Contributed features to a TypeScript-based web product for roof safety systems and solar panel installations planning, enabling customers to design compliant safety systems.
- Implemented solar panel placement features using Entity Component System (ECS) architecture, feature flags, React components, and PDF export based on SVG to improve product modularity and release flexibility.
- Converted Figma designs into reusable, pixel-perfect React components and customized MUI to match brand requirements.
- Built a guided wizard that converts roof area designs into an automated parts list, selecting substructure and solar panel types, orientation, and layout.
Lead Mobile Engineer
Sparwk
- Architected and delivered React Native applications from scratch for iOS and Android, owning mobile architecture, release strategy, and deployment automation.
- Set up Bitrise CI/CD pipelines with automated TestFlight and Google Play releases, reducing manual release effort and improving delivery consistency.
- Architected a reusable component library from Figma designs to accelerate feature delivery and maintain visual consistency.
- Implemented data fetching and caching with Axios and React Query to improve app responsiveness and reduce network calls.
Software Engineer
Codecentric
- Delivered 10+ enterprise web and mobile applications across IoT, logistics, and HVAC, contributing to reusable mobile architecture and faster product delivery.
- Built MVPs with React Native and Django REST framework as part of a rapid prototyping team, helping validate ideas quickly.
- Spearheaded end-to-end product development, including requirements gathering, architecture, implementation, and coordination across stakeholders.
- Developed three IoT mobile apps for Medion—Robots, Pet, and Air—using a shared component library, enabling faster multi-brand deployment and consistent UX.
- Delivered the myVAILLANT Pro HVAC app—myVAILLANT Pro—with three white-label variants, supporting theming and API integration across product variants.
- Established engineering practices such as CI/CD, code reviews, pull request workflows, and pair programming to improve team delivery quality.
Lead Mobile Engineer
Wowflow
- Architected React Native mobile apps from scratch for Android and iOS, owning technical design and release automation.
- Configured App Center CI/CD pipelines for automated builds and releases, improving deployment reliability.
- Built a reusable component library from Adobe XD designs to ensure consistency and speed up feature development.
- Developed photo documentation workflows handling 100+ images per report, with client-side compression and storage optimization for large media sets.
Software Engineer
BPS Systems and Processes
- Maintained and enhanced an invoicing application handling the generation, delivery, and tracking of client invoices, replacing a manual process for internal finance operations.
- Contributed features to a loan auction platform where lenders competed by bidding the lowest interest rate, matching borrowers with the most favorable offers automatically.
- Co-delivered an issue-tracking system with project boards, ticket workflows, and role-based permissions, providing an in-house alternative to commercial tools like Jira.
- Developed and maintained enterprise web applications using Jakarta EE, JSF, PrimeFaces, and MySQL across the full stack.
Experience
Wowflow Mobile App
http://www.wowflow.comVečeras: City Events App (iOS & Android)
https://veceras.appTraining Builder | Platform for Personal Trainer
https://trening.ctrmirkobajic.comEducation
Bachelor's Degree in Computer Engineering and Informatics
University of Banja Luka - Banja Luka, Bosnia and Herzegovina
Skills
Libraries/APIs
React, REST APIs, React Query, Node.js, Playwright, API Development, React Testing Library, Google Maps API
Tools
Expo, Claude, Adobe Experience Design (XD), TestFlight, Git, Claude Code, Codex, Figma, GitHub, Webpack, Prisma
Languages
TypeScript, CSS, JavaScript, HTML, HTML5, ECMAScript (ES6), CSS3, SQL, GraphQL, Java, Python, Swift, XML
Frameworks
React Native, NestJS, Vanilla JS, Redux, Express.js, Django, Jest, Tailwind CSS, Next.js, MUI CSS, Django REST Framework, JSF, PrimeFaces, Cypress
Paradigms
Mobile Development, Continuous Delivery (CD), Continuous Integration (CI), Entity Component System (ECS), UI Design, UX Design, Search Engine Optimization (SEO)
Platforms
Mobile, iOS, Android, Docker, Bitrise, Amazon Web Services (AWS), PostHog
Storage
PostgreSQL, Databases, MySQL, MongoDB, Redis
Other
Mobile App Development, Web Development, Front-end, API Integration, Cross-platform App Development, Google Play Store, App Store Acceptance Process, Performance, Front-end Development, Responsive UI, UI Development, User Interface (UI), Code Review, AI-assisted Development, App Store and Google Play releases, REST API integration, React Native with Expo (EAS Build and Update), camera and photo capture, offline-first local storage and sync (SQLite or WatermelonDB), CI/CD Pipelines, App Store, White Labeling, Offline Caching, Full-stack Development, Agentic Coding, Back-end, Full-stack, Push Notifications, User Authentication, User Experience (UX), Web Scraping, Minimum Viable Product (MVP), Architecture, Technical Leadership, Design Systems, Cloud Infrastructure, AI Integration, AI Tools, Offline Data Synchronization, signature capture, feature flags, Axios, Product Prototyping, Barcode Scanners, Java EE 6, Large Language Models (LLMs), Supabase, Lending, GitHub Actions
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