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 Solutions 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
Founder & Full-Stack Engineer · rixAI
Mar 2026 – PresentNew York City
- Build an AI-powered consumer app end to end, integrating third-party APIs (auth, payments, AI, analytics) into production
- Implemented the subscription and billing flow, handling external payment integration and access control across web and mobile
- Designed and troubleshot AI chat and debate workflows, with monitoring and analytics to diagnose issues and keep sessions reliable for real users
Founder & Engineer · Fitness App
Jul 2023 – Apr 2025France
- Took a cross-platform app from idea to working MVP, then kept iterating after missing the first target, treating it as a hands-on lab for product and growth
- Combined market research, user feedback, and input from a fitness coach to shape training features that improved retention
- Made the build, prioritization, and trade-off calls solo, learning where time pays off and where it does not
Product Engineer · previously Software Engineer · Amblea
Jan 2020 – Jul 2023Paris, France
- Delivered features end to end, from technical scoping and specification through development, testing, and deployment
- Owned incident response, troubleshooting, and migrations with minimal disruption, keeping a customer-facing service reliable
- Improved release and deployment workflows, cutting release time by 40% and raising quality across the team
Frontend Engineer · Boxy
Jul 2019 – Dec 2019Paris, France
- Created the product's mobile visual identity, supporting a €5M fundraising effort
- Built a lightweight demo app that opened partnership discussions with a retailer
Frontend Engineer · Winamax
Jul 2018 – Jun 2019Paris, France
- Shipped France's first bet combinator, expanding what users could do and lifting engagement
- Adapted the product for the Spanish market launch, and mentored three interns through their projects
Full Stack Developer · 31Ten
Sep 2016 – Jan 2017Shanghai, China
- Implemented a WeChat integration and e-commerce sites for an international client entering the Chinese market, working directly with the customer through delivery
- Ran the in-person project handoff with a major agency's project manager and delivered end-user training to drive adoption and reduce support load
/ 05 · Selected Work
Selected work
7 projects
WIPrixAI
WIP
Fitness Tracker App
Winamax MyMatch
Boxy Mobile Application
Amblea Platform
Fortune of Time for Ferragamo
