Freelancer profile translated to English.
Back to original languageAbout Raein
Fullstack developer with 4 years of professional experience.
Full-stack engineer with 5+ years of experience in web and mobile development for high-growth startups and industrial SaaS publishers. Design of real-time systems, AR/CV platforms, and AI applications, from prototype to production for millions of users.
Quantitative background in economics, now focused on secure systems in fintech. Experience Joining a founding team as a principal engineer, taking charge of critical web (React, Next.js) and mobile (React Native, Expo) systems.
- Led the UI redesign and performance optimization, including low-level Kotlin fixes, contributing to retention during growth to 10M users.
- Architected a push notification pipeline, an OTA system, and debugging infrastructure (Sentry), reducing the resolution cycle from 7 days to a few hours.
- Built the entire React frontend for two industrial SaaS platforms.
- Developed real-time camera integration, AR overlays, and CV model management interfaces running in a browser on industrial tablets. Contributed to the Django/Celery backend and ASGI server for asynchronous model training and deployment.
- Presented the platform at VivaTech. End-to-end product engineering: 10+ products released (iOS, Android, web). Implemented a group video conferencing system (WebRTC/JaaS, TypeScript, JWT). Developed a real-time multiplayer server (Django Channels, Redis, PostgreSQL).
- Built a SaaS platform for media content management with real-time synchronization and file integrity verification.
- Designed cross-platform GPS and AR mobile apps for gamified tourism (ReactVision/Viro, Supabase, Deno).
- Developed a React application for statistical analysis and visualization of customer behavior, with a Firebase/BigQuery analytical pipeline.
English
Native or bilingual
Korean
Native or bilingual
French
Native or bilingual
Remote only
Primarily works remotely
Experience
- MathGPT LLCFounding Software Engineer (Contractor)July 2025 - December 2025 (5 months)Founding Software Engineer at MathGPT LLC (2025)Edtech startup founded by Cornell alumni, serving over 10 million students with AI-powered step-by-step solutions and video explanations in STEM fields. Valued at $25 million.
- Joined the team as one of the founding engineers; took end-to-end ownership of several critical systems on the web (React, Next.js) and mobile (React Native, Expo).
- Led the UI redesign and performance optimization, including critical low-level Kotlin code fixes, directly contributing to user retention during a key growth phase to reach 10 million active users.
- Designed and deployed the push notification pipeline and an OTA update system for the mobile app, reducing deployment friction for 10 million users.
- Implemented debugging infrastructure with Sentry, reducing the cycle from user bug report to resolution from 7 days to a few hours.
- HoloMakeFull-stack EngineerOctober 2021 - Today (4 years and 8 months)Île-de-France, FranceLead Full-Stack Engineer at HoloMake via Waven Consulting (2021 – 2024)French industrial SaaS startup, accelerated at Station F as part of LVMH's La Maison des Startups. Uses augmented reality and computer vision to guide operators on manual tasks without headsets. Clients include: C-Logistics (Cdiscount), SNCF, Lectra, and Diptyque Paris.
- Developed entirely from scratch the React frontend for HoloMake Studio and Composer, the SaaS platforms at the core of augmented industrial operations.
- Designed the real-time camera integration, AR visual overlays, and computer vision model management interfaces, running natively in the browser on factory-used tablets and smartphones.
- Presented and demoed the platform at VivaTech alongside partners like SNCF and Orange Labs.
- Contributed to the product's pivot towards a mobile-first visual AI platform, bridging AR guidance with a computer vision/machine learning pipeline for industrial defect detection.
- Participated in the development of the Django/Celery backend (REST API) and the Daphne ASGI server for asynchronous training and deployment of computer vision models.
- MindQuest GamesSoftware ConsultantFebruary 2022 - July 2024 (2 years and 5 months)Independent Technical Consultant for Mindquest Games (2022 – 2024)Publisher and organizer of gamified education and local tourism products. Clients include: the French Building Federation, PROBTP, and MAE (through tenders).End-to-end product engineering for the entire application ecosystem and associated IT infrastructure.
- Designed and delivered over 10 commercialized and released products, including Le Labyrinthe de Nina (iOS, Android), jouer.escapelaicite.com, and other digital escape games, developed with React, React Native, and Django.
- Implemented a robust group video conferencing feature (JaaS/WebRTC, fully typed custom TypeScript library) backed by a Django backend acting as a trusted JWT signing authority, linking the identity and permissions of each participant to their registered game profile.
- Developed a scalable real-time multiplayer game server based on Django Channels (ASGI/WebSocket) and Redis as a message broker, managing the complete lifecycle of a game between simultaneous teams with persistent state in PostgreSQL and transactional state management.
- Developed the SaaS platform used by clients to upload, manage, and edit media content and subtitles, delivered to content-rich mobile applications. Real-time synchronization ensures that resources downloaded to user devices always match the latest published content, using a custom TypeScript library implementing a checksum integrity verification algorithm within Expo React Native applications.
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Education
- Bachelor of EconomicsUniversity of Reims Champagne-Ardenne2021Statistics & data studies