Guillaume Breux, Developer in La Massana, Andorra
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Guillaume Breux

Verified Expert  in Engineering

JavaScript Developer

La Massana, Andorra
Toptal Member Since
July 23, 2018

Guillaume is a customer-centered front-end developer leading with agility and a designer’s eye for detail to deliver an optimal user experience. He transforms an idea from conception to application to revenue driver, making thoughtful business and design decisions throughout development and lifecycle. Guillaume is a humble team player leading by influence and genuine passion for crafting solutions by speaking the languages of designers, developers, and users in fostering smart collaboration.


Front-end Development, React, JavaScript, Product Management
Wanted—Acquired by Revolut
Next.js, JavaScript, Product Management
Webflow, Jekyll, Angular, React




Preferred Environment

VSCodium, Git, MacOS

The most amazing...

...thing I've built is a company trying to improve the way companies hire people with a more transparent and fair approach.

Work Experience

Front-end Developer | Team Lead | Tech Recruiter Support

2015 - PRESENT
  • Designed and implemented a Web3 NFT project on the Ethereum blockchain.
  • Selected, tested, interviewed, and led a UI developer in helping scale a company maintaining a user-focused culture.
  • Made the data-backed business case for a company to deploy a more user-focused approach to services. The effort resulted in hiring a designer and a UI developer and the development of team-centered processes.
  • Trained engineers and designers on design tools like Figma, fostering a shared language and improving overall collaboration.
  • Joined the Toptal exclusive network and wrote a paper in their highly respected blog for the occasion.
  • Redesigned and integrated a 20-year-old, highly specialized media platform in the French healthcare industry.
  • Onboarded and coached a developer with specific knowledge that enabled project independence.
Technologies: Front-end Development, React, JavaScript, Product Management

Co-Founder and CXO

2019 - 2021
Wanted—Acquired by Revolut
  • Delivered an international web application, managed its development, and scored 100% on the last performance rating technologies.
  • Implemented the front-end architecture for all necessary services and developed Chrome plugins for growth hacking and moderation.
  • Executed strategy, testing, refinements, and a privacy-first approach, gathering direct feedback from talents and companies.
Technologies: Next.js, JavaScript, Product Management

Lead Front-end Developer

2015 - 2019
  • Played a key role in the startup’s success and the holistic web experience that led to the $18M sale of Once.
  • Adapted design to an optimized desktop version that outperformed both iOS and Android KPIs for LTV, acquisition cost, traffic to lead, and key actions.
  • Built the CRM strategy to send customized, thoroughly tested emails to 9 million guests.
  • Implemented a front-end development strategy to minimize the need for a DevOps team, forging a fully independent service at a meager cost using a serverless AWS strategy.
  • Collaborated with the product team on new features, making a case for changes and gathering data to verify hypotheses.
Technologies: Webflow, Jekyll, Angular, React


2010 - 2015
  • Helped deliver a commercial for Samsonite, working with cinema-grade equipment.
  • Found relevant spots and advised lights and equipment to create the art project—Queer Kids—documenting LGBTQ youth in Belgium.
  • Edited a complete set of fine art pictures for high fidelity print.
  • Automatized a setup to deliver a couple of thousand luxury hats pack-shots.
Technologies: Product Photography, Global Project Management


We started Wanted to make sure people get paid what they deserve, regardless of gender, race, or how well someone negotiates.

It is the first platform designed to poach the best talent at their desired salary.


• $2m Pre-seed from Hoxton, Partech & Kima
• 100k+ vetted talent @ CPA under $3
• Beta clients: Facebook, Lodestone, Cembra among others

Once Dating
Once is the number 1 slow dating service in Europe with 9 million users.

I joined Once pre-product and was in charge of making sure our guests browsed the web version like they were using a native application and developing all the web services the company needed. Every decision was made to improve the holistic experience that led to an $18 million exit.


SCSS, CSS, HTML, JavaScript, Less


Next.js, Redux, Angular


Flexbox, React, Web3.js


Sketch, Figma, Git, IntelliJ IDEA, Jekyll


BEM, Search Engine Optimization (SEO)


Serverless, SVG, Responsive UI, Front-end Development, Front-end Architecture, CSS Grid, Product Management, VSCodium, Creativity, Computer Graphics


Webflow, MacOS

2014 - 2015

Professional Degree in Web Design and Front-end Development

CEPEGRA | Center Competence Forem Cepegra - Brussels, Belgium

2010 - 2013

Bachelor's Degree in Photography

INRACI | Institut National de Radioélectricité et Cinématographie - Brussels, Belgium

2009 - 2010

Coursework Completed Toward a Bachelor's Degree in Computer Graphics

HEAJ | Haute École Albert Jacquard - Namur, Belgium

Collaboration That Works

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