Web developer · BarcelonaFull-Stack Developer — Barcelona

LeonAves

I design and build fast, beautiful websites and apps, and look after them once they're live. Based in Barcelona, working with clients everywhere. TypeScript, React and Node.js, end to end. Nearly two decades shipping product for startups and scale-ups across the UK and Europe.

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Websites
Web Apps
Online Stores
Redesigns
Hosting & support

AboutAbout Me

I'm Leon, a developer with nearly two decades of experience building websites and apps for companies across the UK and Europe, from small local businesses to platforms trusted by thousands of companies.

I can handle the whole job: planning, design, build and launch, or just the parts you need help with, I have plenty experience working on my own or on large projects with a team.

I also build and run my own products, so I know what's needed to keep things growing and in good shape.

I'm a full-stack developer with nearly two decades of experience building web applications that users love. After graduating from York University with a degree in Computer Science, I've been crafting digital solutions for companies across the UK and Europe.

My toolkit centres around TypeScript, React, and Node.js, deployed on cloud platforms like AWS and GCP. I particularly enjoy tackling complex frontend challenges, whether that's optimising performance for smart TVs or architecting scalable micro-frontend systems.

When I'm not working with clients, I'm building my own projects. I love the process of taking an idea from concept to thousands of daily users.

How I can help

Websites that load fast and look great on any screen
Apps, booking systems and online stores
Speeding up or modernising an existing site
Hosting, updates and ongoing support

Technologies I work with

Frontend: TypeScriptReactNext.jsRSCMicro-frontends
Backend: Node.jsGraphQLApollo Federation
Data: PostgreSQLMongoDBD1
Infra: AWSGCPCloudflare WorkersR2

Where I've worked

Lokalise

Current

Senior Software Engineer, building Lokalise's new editor — the tool that more than 3,000 companies, including Revolut, Notion and Mastercard, use to translate their apps and websites into other languages.

Working as a Senior Software Engineer on Lokalise's new editor experience. Lokalise is a translation and localization platform trusted by over 3,000 companies including Revolut, Notion, and Mastercard to manage multilingual content across apps, websites, and digital products.

Visit Lokalise

wi-Q

Led the front-end team at this hospitality tech company, rebuilding the app guests use to order food and drink from their table — including “Pay at Table”, which lets a group watch their bill update live and split it however they like.

Led frontend engineering. Re-architected the mobile ordering platform around micro-frontends and React Server Components, and shipped “Pay at Table”: real-time tab syncing and multi-user bill splitting.

ReactRSCMicro-frontendsReal-time

Visit wi-Q

Feedr

Led a team of developers rebuilding Feedr's group ordering product — how offices order lunch together — from the ground up, and set up the shared building blocks that kept the whole product looking and working consistently.

Led the squad rebuilding group ordering from scratch. Designed an Apollo Federation GraphQL architecture, and established the shared React component library the micro-frontends are built from.

GraphQLApollo FederationReactMicro-frontends

Visit Feedr

Fiit

Senior engineer at the home-fitness company, working on live multiplayer workouts and leading the apps people use on their TVs and in the browser — making them smooth on everything from a budget streaming stick to a smart TV.

Senior engineer on the core API and multiplayer workout features. Led the TV and web apps, optimising performance across platforms from Amazon Firestick to Samsung Smart TVs.

APIMultiplayerSmart TVPerformance

Visit Fiit

Other projectsOther Projects

Cropple

A daily picture puzzle: guess the word as more and more of a photo is revealed. I built it on my own in 2025, and thousands of people now play it every day.

A daily word puzzle where players guess words from progressively revealed image crops. Solo build in 2025, running entirely on Cloudflare — Workers, D1 for game state, R2 for images — for thousands of daily players.

ReactTypeScriptWorkersD1R2

Play Cropple

Velo

A privacy platform I co-founded. It puts everything a website needs for cookie consent in one place. Less privacy admin, more control.

A consent management platform I co-founded and lead technically, with a cookie and tracker scanner and an append-only consent log on Postgres, served from Cloudflare Workers and installed through a GTM template.

PreactWorkersPostgresConsent Mode v2

Visit Velo

LemonArc

The web design and hosting agency I co-founded. We've built and looked after websites and online shops for more than 50 small businesses.

A web development and hosting agency I co-founded. We've helped over 50 small businesses establish their online presence with custom websites, e-commerce solutions, and ongoing hosting and maintenance.

WordPressE-commerceHosting

Visit LemonArc

Let's work togetherGet in Touch

Need a new website, a web app, or a hand with the one you've already got? Tell me a little about your project.

I'll get back to you as soon as I can with next steps.

I'm currently available for freelance projects and consulting work. Whether you need a complete web application, frontend expertise, or technical guidance, I'd love to hear about your project.

Drop me a message and I'll get back to you as soon as possible.