Full-stack TypeScript development, from the interface to the API
I build web applications in TypeScript end to end, frontend and backend, fully remote. WorkoutGen, the app I co-founded, was built in TypeScript from its React interface to its Hono API on Cloudflare Workers.
TypeScript projects I built
Two products I built end to end, and client applications from startups to Sciences Po.
Personalised workout generator
One TypeScript codebase serves more than 51,000 members on the web, iOS, Android and Windows (workoutgen.app, October 2026)
Open-source agentic RAG for coding agents
Coding agents search your code and documents locally and get cited passages, through a TypeScript library, CLI and MCP server on npm
Sciences Po's thematic mapping tool
Datasets of up to millions of rows become maps without leaving the browser: SQL in a Web Worker, then a binary pipeline from the query to the GPU. A complete rewrite designed by the Cartography Lab, which I developed
B2B prospecting platform, web and mobile
Sales teams find leads on the web, iOS and Android, through one React and TypeScript codebase I built from scratch
Institutional design system for React and Angular
Web Components written once in TypeScript with StencilJS, then wrapped for the school's React and Angular applications
Real-time AI meeting assistant
Key points appear while the meeting is still under way, in a Next.js and TypeScript interface fed live over WebSocket
One language from the interface to the server
TypeScript is my everyday language, on the frontend and the backend alike. Types shared from the interface to the database, through tools such as Drizzle ORM, mean a mismatch breaks the build or the tests, not production.
I adapt to the framework and tools your codebase already uses, and keep the types reliable where data enters, with strict compiler settings, validation and Vitest tests.
Fundamentals
- JavaScript
- DOM
- Browser APIs
- Node.js runtime
- npm
Possible deliverables
- A TypeScript application, frontend and backend, or either side within your team
- Node.js APIs with Hono or Fastify, with typed access to PostgreSQL or Cloudflare D1
- Types shared between the interface, the API and the database
- Vitest and Cypress tests in continuous integration
- Takeover and maintenance of an existing TypeScript application
- Engagement
- Team support, project or application takeover
- Schedule
- Agreed for the engagement
- Indicative rate
- €550 excl. VAT / day (October 2026)
- Collaboration
- Fully remote
- Start date
- To be agreed
My main language, frontend and backend
Every client project on this site from 2020 to 2026 has TypeScript in its stack, frontend or backend.
I learnt to keep a codebase typed, tested and reviewed on projects delivered before AI coding tools, and I hold the code I now write with coding agents to the same rules.
Through jCode, I work with public institutions, established companies and startups. My own products, WorkoutGen and Ragmir, taught me what follows a release.
- of web development
- 10 years
- missions completed on Malt (November 2026)
- 80+
- as a freelancer
- 7 years
- from 47 client ratings on Malt (November 2026)
- 5.0/5
Other areas of expertise
What clients and colleagues say
“I strongly recommend working with JB. He was instrumental in getting our frontend off the ground, handling everything with zeal, unwavering dedication, and unparalleled reliability.”
LinkedIn“On top of being very up-to-date with all techs and stacks front, he is a very creative software engineer who will use his curiosity to try and offer the best solution possible for the problem, without sticking to his guns.”LinkedIn“Jean-Baptiste nous a aidé dans le développement frontend de notre outil Sweez. C'est un développeur talentueux et hautement compétent. Son expertise technique et sa capacité à résoudre les problèmes de manière créative font de lui un atout précieux pour toute équipe de développement. Il est fiable, consciencieux et démontre une grande attention aux détails dans son travail. Il communique bien et est force de proposition. La qualité de son code et sa capacité d'adaptation sont remarquables.”
MaltLet's talk about your project.
Tell me what you want to build or improve, your budget and your target date.
- Fully remote
- English or French
- France · UK · US
Frequently asked questions
Do you also write the backend in TypeScript?
Yes. I built WorkoutGen's API with Hono on Cloudflare Workers, Drizzle ORM and D1, and Ragmir as a Node.js library and CLI. I have also worked with Fastify and Strapi, and on Java and Symfony backends.
Can you join a TypeScript team for the frontend only?
Yes. My engagements at Leadbay, Sweez and Stellia.ai covered the frontend only, in React and TypeScript, within each team's conventions, reviews and tests.
Can you take over an existing TypeScript codebase?
Yes. I first review the code, types, dependencies and tests, then we agree priorities and an estimate before any change. The audit and recovery service starts with this review, at a fixed price.
Do you use AI coding tools on TypeScript projects?
Yes, within each client's rules: same type checks, same tests, same review. WorkoutGen, built with coding agents such as Claude Code, had 547 automated test files (October 2026). The agentic development page sets out how your code is handled.