ThomasJosso
I build web and mobile products end to end, from architecture and APIs to the screens people actually use. Eight years of it, across startups and growth-stage teams.
- 8+
- Years Experience
- 20+
- Projects Delivered
- 5+
- Companies Served
- 3
- Countries Worked
Based in New York City
Available for Freelance & Contract
/ 02 · About
A bit about me
I'm a Full Stack Engineer who cares about the whole picture, from how the API is structured to how the button feels to tap.
Eight years in, and I've had the good fortune of building across Paris, Shanghai, and New York: at startups raising their first round, at companies shipping to millions, and on my own projects at 2am. That range of context is probably my biggest asset.
I gravitate toward the messy middle: products that are technically interesting AND have to actually work for real people. I care about performance, I care about the handoff, and I'll always push back when something ships wrong.
Expertise
- Full Stack Development
- Mobile Applications
- System Architecture
- Technical Leadership
Industries
- AI & Machine Learning
- Health & Fitness
- E-commerce
- FinTech
Education
- Engineering Degree
- Computer Science
- EPITA, Paris
Languages
- French (Native)
- English (Fluent)
/ 03 · Approach
How I work
Four things I bring to every engagement.
Strategy & Architecture
Before I write a line of code I want to understand the business constraint. I'll map the architecture to your actual growth trajectory, not the theoretical one.
Full Stack Development
I build full-stack: React or React Native on the front, whatever is right on the back, connected properly. I care that it works on a slow phone in bad cellular, not just on my MacBook.
Technical Leadership
I've led small engineering teams and I've been the lone engineer. Either way I write specs, I review code like it matters, and I try to leave the codebase better than I found it.
DevOps & Reliability
Shipping is not the finish line. I set up CI/CD that actually catches things, write tests that document intent, and keep the observability in place so you know when something breaks before your users do.
/ 04 · Experience
Where I've worked
Download full résumé (PDF)Technical Lead (Founder) · rixAI
Mar 2026 – PresentNew York City
- Implement a strict TypeScript monorepo with Turborepo and pnpm, integrating an Expo mobile app (Expo Router) and a Next.js web app (App Router) that share a tRPC API, Neon PostgreSQL via Drizzle ORM, and Zod v4, enabling consistent code reuse across platforms and reducing development time
- Use TanStack Query and Zustand in mobile clients, sharing API types from the server through tRPC, which streamlines state management and improves data synchronization performance
- Design authentication with Supabase, supporting Google, Apple, magic-link flows, and optional Upstash Redis for sessions, caching, and rate limiting, providing a secure and flexible login experience that reduces authentication latency
Technical Lead (Founder) · Fitness App
Jul 2023 – Apr 2025France
- Developed a viable MVP in the first year and, after missing the target, continued the project as a personal lab to explore new technologies, strengthening full-stack development skills
- Designed and developed an isomorphic mobile and web app from scratch using React Native and Next.js, delivering a cross-platform experience that improved user engagement
- Built a GraphQL API with MySQL and implemented multi-platform CI/CD pipelines, reducing deployment time and increasing release reliability
Product Engineer · previously Software Engineer · Amblea
Jan 2020 – Jul 2023Paris, France
- Delivered features from technical specification drafting to development, testing, and deployment, ensuring seamless integration and improved user satisfaction
- Built automated unit, integration, and regression tests in TypeScript, improving release stability
- Developed with React, Next.js, and React Native to enhance usability and performance, resulting in a more intuitive user experience and faster application load times
Frontend Engineer · Boxy
Jul 2019 – Dec 2019Paris, France
- Implemented React Native tech stack for scalable and rapid delivery
- Created a consistent mobile visual identity, supporting €5M fundraising efforts
- Built a lightweight web app for a retailer demo, leading to partnership discussions
Frontend Engineer · Winamax
Jul 2018 – Jun 2019Paris, France
- Built France's first bet combinator, expanding available betting options and enhancing user engagement
- Updated the interface for the Spanish market launch, improving user experience and accessibility
- Supervised and mentored three interns during their projects, fostering skill development and ensuring project success
Full Stack Developer · 31Ten
Sep 2016 – Jan 2017Shanghai, China
- Built a WeChat app for a luxury brand to reach the Chinese market, enhancing brand visibility and customer engagement
- Maintained three e-commerce sites and ran targeted ad campaigns for China, increasing site traffic and boosting sales
- Conducted an in-person project wrap-up with the project manager of a major marketing agency, ensuring final approval and client satisfaction
/ 05 · Selected Work
Selected work
7 projects
WIPrixAI
WIP
Fitness Tracker App
Winamax MyMatch
Boxy Mobile Application
Amblea Platform
Fortune of Time for Ferragamo
