Frontend & UI engineering
Responsive, accessible interfaces with React, Next.js and TypeScript, with proper attention to UI and UX. Pixel-perfect from Figma, down to the details designers notice.
Freelance React developer in Amsterdam
Freelance full-stack engineer in Amsterdam, focused on the front-end, with 6+ years of shipping production web apps. I often design the UI/UX myself, use AI tools like Claude Code daily, and care about the fundamentals: maintainability, performance and code your next developer can work with.
Brands I've built for
Ways to work with me
I need a freelancer
Extra senior capacity in your product team, for a sprint or a full release. You hire me directly, no agency in between.
How hiring me works →
I'm hiring full-time
Looking for a senior front-end engineer for your team? Here's where I have worked so far.
See my experience →
Our codebase slows us down
A short audit of your React app first, then fixes in order of impact.
Ask for an audit →He created impact by completely setting up a new front-end for a service that is used by 100+ internal users, well within the deadlines. He is the first I will call when I've got another assignment for him.
Koen van Rijswijk Engineering Manager at bol.com Read the bol.com case →
Selected work
See all 23 cases booming.jobs
Booming Jobs is a Dutch job platform for blue- and grey-collar work in logistics, technical trades and production.
Ongoing View case →
quartou.com.br
Quartou is a room rental marketplace for the Brazilian market. Tenants search rooms and apartments across the country, while landlords list their…
Ongoing View case →
Ben.nl Redesign/UI Library
Ben is one of the biggest budget telecom brands in the Netherlands, part of Odido (the former T-Mobile NL).
View case →
CZ Vergoedingen
CZ is one of the largest health insurers in the Netherlands. The vergoedingen platform is where customers check what their policy covers: which…
View case →
What I do
Design systems & components
Component libraries that keep products consistent: Storybook-documented, accessibility-audited, themable. I built them for CZ and Ben.nl, and I publish my own open source library.
See sander-ui →Full-stack delivery & rescue
API design, data modelling and backends in Node.js and NestJS, plus Java and Kotlin when needed (I built backend-for-frontend services at Bol.com). I also audit and fix existing codebases that slow teams down.
UI/UX design
For most projects I design the interface myself, from wireframe to final screens. No separate designer needed, and no handoff friction between design and code.
SEO & landing pages
Landing pages that load fast and rank: technical SEO, structured data, Core Web Vitals and a clear content structure. This site scores 100 on Lighthouse, and yours can too.
Something else?
Send me a short description of the project and I'll tell you if I can help.
Get in touchFaster with AI
I use Claude Code daily to multiply my productivity: AI writes a lot of the boilerplate, while I do the architecture and review everything that ships.
This site is an example: designed and built with Claude Code, scoring 100 on Lighthouse. These are its latest commits.
$ git log -3b5be737 Rebuild front-end inhuren page, share hire-page components, fix contrastCo-Authored-By: Claude Opus 5.5 (1M context)f02193a Update front-end inhuren page to the €90 rateCo-Authored-By: Claude Opus 5.5 (1M context)569b0ad Redesign site: navy/green system, remove AI-looking patterns, rebuild React inhuren pageCo-Authored-By: Claude Opus 5.5 (1M context)Recommendations
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Sander is a highly skilled and talented developer who delivers good work. His communication is excellent and he has a remarkable ability to work independently — efficient, reliable and always on top of things.
Andrey Posudevsky Full-Stack Web Developer / Architect -
Sander does not shy away from a challenge and has an open, calm working attitude — focused on delivering business value without losing sight of quality. A very pleasant collaboration.
Peter Bust Senior Frontend Developer, React / Next.js -
Sander reinforced our frontend team midway through an ongoing project within an existing multidisciplinary team. He found his way quickly, keeps his agreements, and is well up to date with the latest best practices in JavaScript and Nuxt.
Johannes Hartman COO / Partner, NOBEARS Group -
He's very serious about his code quality and works very hard. Reviewing his code is swift and easy — it's high quality and there's not much to improve upon.
Wijnand Karsens Full-Stack TypeScript Engineer -
His skills are exactly what you're looking for in a frontend developer. He's forward-thinking, eager to learn and open to ideas and feedback. I'd certainly recommend him for any JavaScript-based project.
Ruben Kuipers Senior UX/UI Designer & Frontend Developer
Experience
- Nov 2025 – now
Senior Frontend Developer
BOOMING.JOBS
- Oct 2024 – Jun 2025
Senior Frontend Developer
Klein Media
- Apr 2024 – Jun 2024
Senior Frontend Developer
Collabhouse
- Oct 2023 – Mar 2024
Senior Front-end Developer (React, Next.js)
bol.com
- Jun 2023 – Oct 2023
Senior Full-stack Developer (React, Node.js)
narratives.tech
- Mar 2022 – Feb 2023
Senior Front-end Developer (React)
CZ
- Mar 2022 – Sep 2022
Senior Front-end Developer (HTML, Twig)
T-Mobile Nederland
- Feb 2022 – Mar 2022
Freelance React Native Developer
The Recharge Company
- Dec 2021 – Feb 2022
Freelance Vue.js Developer
Bitfactory
- Oct 2021 – Apr 2022
Senior Front-End Engineer (React)
Wunderman Thompson Commerce
- Apr 2021 – Nov 2021
Freelance React Developer
Growyze
- Apr 2021 – Nov 2021
Freelance Vue.js Developer
Puppyplaza.com
- Feb 2021 – Jun 2021
Front-end developer (React)
Luggage Care
- May 2020 – May 2020
Fundamentals + Advanced React Training
React/GraphQL Academy
- Oct 2019 – Dec 2019
Young Professional Academy (YPA)
Incentro
- Oct 2019 – Feb 2021
Front-end developer (React)
Incentro
- Jan 2017 – Sep 2018
MSc Strategic Entrepreneurship
Erasmus University Rotterdam (RSM)
- Oct 2013 – now
Internet entrepreneur
Sanvar
- Sep 2011 – Dec 2016
BSc Business Administration
Erasmus University Rotterdam (RSM)
Coding activity
Last 12 months via WakaTime