Driving Impact
I build things that work. My goal is to create solutions that solve real problems and provide a smooth experience for users. I focus on delivering value that makes a difference.
Currently at Keolis Group
Frontend Engineer for High-Traffic E-commerce
Working remotely at Keolis, previously Decathlon e-commerce across 15+ markets. I build accessible, high-performance storefronts and design systems with React, Next.js and Svelte.
About me
Hi, I'm Kévin Sauvage
Currently at Keolis Group (remote) — accessibility at scale, axe in CI
Frontend Engineer at Keolis Group (remote), based in Barcelona, with 5+ years building web products used by millions across 15+ countries, including Decathlon's e-commerce platforms in Europe. I mostly work with React, Next.js, Svelte and TypeScript, and I care a lot about accessibility, testing and keeping codebases maintainable. I'm comfortable owning features from start to finish in fast-moving teams.
Languages
- FrenchNative
- EnglishC1 Certified
- SpanishFluent
My Philosophy
Code Quality
I write clean, maintainable code and keep learning new tools and techniques to build better solutions. Good code saves time and makes everyone's job easier.
Collaborative Growth
I work best with others. I enjoy teams where we share knowledge, communicate openly, and help each other grow through feedback and collaboration.
Career
Professional Journey
Each role I've had has pushed me in a different direction. From building component libraries to tuning performance and accessibility, every step has made me a more well-rounded engineer.
Keolis Group
Frontend Software Engineer
Feb 2026 – PresentIntegrated Jest-axe and Cypress-axe into the CI/CD pipeline, preventing accessibility regressions from reaching production.
Enforced WCAG compliance at the source by configuring ESLint (jsx-a11y + custom rules) as a required gate on every pull request.
Refactored core UI components to enforce semantic HTML, ARIA, keyboard navigation, and screen reader standards.
Collaborated with product and design to make accessibility a first-class requirement from wireframe to release.
Next.jsReactTypeScriptTailwindJest-axeCypress-axeESLintjsx-a11yARIASemantic HTMLAccessibility
Decathlon Core
Frontend Software Engineer
Oct 2023 – Feb 2026Architected a Svelte component library now powering e-commerce storefronts across 15+ countries, standardising UI at scale.
Drove A/B testing initiatives that produced measurable lifts in conversion and user adoption across international markets.
Worked closely with designers in Figma and Storybook to ship pixel-perfect, accessible components with high test coverage.
Owned the full test suite (Jest, Cypress), raising coverage and reducing the rate of production incidents significantly.
SvelteJavaScriptStorybookJestCypressFigmaTailwindAccessibility
Decathlon Spain
Frontend Software Engineer
May 2022 – Oct 2023Improved Core Web Vitals on the Decathlon Spain storefront, cutting average load time by 1.5s and lifting Lighthouse scores.
Built a modular Svelte component system that cut duplication and accelerated delivery of new product features.
Rolled out WCAG 2.1 accessibility standards across the platform, meaningfully improving the experience for all users.
Established internal documentation standards for components and technical decisions, improving team knowledge sharing.
SvelteJavaScriptCore Web VitalsTailwindPerformanceAccessibility
Subforce
Frontend Software Engineer
Jun 2021 – May 2022Delivered full-stack features using React.js, Next.js, Node.js, and Express.js, including secure third-party API integrations.
Designed scalable state management patterns with Redux and Context API, improving data flow across complex UIs.
Modernised a legacy JavaScript codebase to ES6+ standards, cutting bug count and improving long-term maintainability.
ReactNext.jsReduxNode.jsExpress.jsMongoDBJavaScriptSass
Testimonials
What Colleagues Say
A few words from colleagues and managers I have had the chance to work with.
01 / 03
"From day one, he showed a rare ability to take on the most complex technical challenges and find pragmatic solutions. His ability to adapt quickly, understand the bigger picture, and deliver impact made him an invaluable asset in both contexts. I would gladly work with Kevin again — any organization would be lucky to have him."
Portfolio
Featured Projects
Here are some projects I've worked on. Each one is focused on speed, accessibility and real usability, and reflects how I think through problems and build things that hold up in production.
01
Modern E-Commerce Platform
A modern e-commerce demo built with Next.js 15 and TypeScript. Features product filtering, cart management, and checkout powered by Shopify's Storefront API. Achieves high Lighthouse scores for performance, accessibility, and SEO.
Next.jsReactTypeScriptShadCnTailwind CSSGraphQLShopify Storefront APIZod
Credentials
Continuous Learning
Production work is my main credential — these formalize the rest. Right now that means accessibility depth, JavaScript fundamentals, and working across three languages.
Deepening Web Accessibility
Self-directed · In Progress
•Going deeper on WCAG 2.2, ARIA authoring practices, and screen-reader testing — applied directly to Keolis delivery and axe-gated CI pipelines.
WCAG 2.2ARIAScreen Readers
C1 English Certificate
EF SET
•Official C1 Advanced English certification for professional communication in international environments.
C1 Advanced EnglishInternational Collaboration
View Credential for C1 English CertificateReact: Using TypeScript
LinkedIn Learning
•Course on building type-safe React applications with TypeScript — props, hooks, and patterns for complex front-ends.
ReactTypeScriptType Safety
View Credential for React: Using TypeScriptJavaScript: The Advanced Concepts
Udemy
•Advanced JavaScript course covering closures, prototypes, async programming, and modern ES6+ features for complex applications.
Closures & PrototypesAsync PatternsES6+
View Credential for JavaScript: The Advanced ConceptsFull-Stack Web Developer Bootcamp
Le Wagon
•Where I started: 9-week intensive bootcamp covering Ruby on Rails and JavaScript. Since then, 5+ years of production React, Svelte, and Next.js work.
Full-Stack FoundationsRuby on RailsJavaScript
View Credential for Full-Stack Web Developer BootcampFAQ
Questions, Answered
The things people usually ask before getting in touch — answered upfront so you don’t have to.
I'm currently a Frontend Engineer at Keolis Group, working remotely from Barcelona — and I'm always open to connections and interesting conversations. The fastest way to reach me is the contact form or email below; I reply within 24 hours on weekdays.
My day-to-day focus is my full-time role at Keolis, so I only consider small, well-scoped collaborations — audits, code reviews, or mentoring. Tell me what you have in mind and I'll give you a straight answer.
React, Next.js, Svelte, and TypeScript, with Tailwind CSS, Storybook, and testing built on Vitest, Cypress, and axe. My specialties are accessible e-commerce at scale, design systems, and Core Web Vitals performance.
Yes. Decathlon and Keolis work is proprietary, but I can walk through NDA-friendly summaries: architecture decisions, metrics like the −1.5s LCP improvement, and lessons learned. Just ask.
Barcelona, Spain (CET, UTC+1), working remotely. I work in French (native), English (C1 certified), and Spanish (native) — comfortable in multicultural, distributed teams.
Contact
Let's connect
Based in Barcelona, working remotely at Keolis Group. Always open to interesting conversations and opportunities — feel free to reach out.
Barcelona, Spain — CET (UTC+1) · English, French, Spanish