Antoine Duvauchelle Product Engineer · Paris

Summary

I build design systems, polished UI, and the guardrails that let teams — and agents — ship them. Ten years shipping production frontends, from startup studios to the booking funnel of Rail Europe. I care about the last 10% (interaction details, accessibility, perceived speed) and about making the right path the easy one for whoever builds next.

Experience

  1. Rail Europe 2024 — now

    Senior Software Engineer — B2C revamp & mobile 2025 — now

    Revamped the ten-year-old Rails B2C platform (CoffeeScript, jQuery, React SPA) toward a modern Rails and Hotwire stack, took over the mobile apps with Capacitor, cut the front bundle by 40% and the critical booking pages by 1.3 s on average.

    Case study: toyn.dev/work/rail-europe-migration

    Software Engineer & Scrum Master — SvelteKit rebuild 2024

    First in-house engineer on a from-scratch SvelteKit rebuild of the B2C site, alongside Mainmatter consultants. Developer, Scrum Master and team facilitator for 21 people; the project was stopped at around 80% in favour of revamping the existing platform.

    Case study: toyn.dev/work/rail-europe-sveltekit

  2. Holivia 2022 — 2024

    Frontend Engineer 2022 — 2024

    Revamped the whole frontend of the mental-health platform's Rails app, set up unit and feature testing, and built in-house libraries for the audio player (guided sound sessions) and therapist video calls.

    Case study: toyn.dev/work/holivia

  3. Freelance 2016 — 2021

    Full-stack developer — In the Memory 2021

    Built, maintained and customised a retail data-visualisation tool (Rails + React) for the startup's major client.

    Full-stack developer — Atelier des Giboulées 2020 — 2021

    Designed and built Mallapixels, a Rails app for the Val-de-Marne libraries to lend digital devices, and accessible, eco-designed content sites in SvelteKit for the Agence Parisienne du Climat and the Clong.

    Frontend developer — Cultur'In the City 2019 — 2020

    Maintained and improved the Next.js app; continuous e-commerce performance and SEO audits.

    Frontend developer — Majelan 2018 — 2019

    Built the podcast back-office in Vue.js, then merged the internal tools into a single React back-office with an Atomic Design architecture.

    Brand identity & Product builder — Slash Lab 2016 — 2018

    Ran brand-identity workshops with startup founders (Kawaa, Dress in Peace, Base Jaune) and wrote their brand platforms — identity, mission, tone of voice, social proof — which the art director turned into logos, visual identity and product experience. Then implemented it in CSS and quick frontend prototypes in Rails MVPs.

Projects

Skills

Frontend
TypeScript, JavaScript, HTML, CSS, Svelte, SvelteKit, React, Next.js, Vue.js, Hotwire, Turbo, Stimulus, Tailwind
Design systems
Storybook, design tokens, Atomic Design, accessibility
Backend and mobile
Ruby on Rails, Capacitor, DatoCMS
Testing and tooling
Playwright, Vitest, Biome, Bun, zod, D3
AI
Claude Code

Languages

French (native) · English (fluent) · Spanish (intermediate) · German (basic) · Japanese (basic)

Education