My name is Leonardo Maldonado. Software engineer from Brazil, based in Valencia, Spain. 7+ years building for the web — from early-stage startups to international product companies.
Creator of 33 JavaScript Concepts — helped thousands of developers to learn JavaScript, translated into 40+ languages, recognized by GitHub as a top open-source project of 2018.
- For four and a half years, the sole frontend engineer on Spaceship domain search at Namecheap — helped the platform sell 3M+ domains.
- Written 100+ technical articles on JavaScript, TypeScript, React, and Node.js for LogRocket and Progress.
- I build things across languages — JavaScript, TypeScript, Go, Rust — because shipping is how I learn.
- 33-js-concepts — 33 JavaScript concepts every developer should know. 66K+ stars and translated into 40+ languages by the community.
- Shopwyse — An ERP I built for retailers who need POS, inventory, CRM, and financial reporting under one roof. TanStack Start, Elysia, PostgreSQL.
- Polyglot — An AI writing assistant that interviews you first, then drafts content in your voice from different angles.
- Otis Finance — A stock market API for real-time prices, SEC filings, earnings, and financials.
- gone — I wanted a dead link detector that was actually fast, so I wrote one in Go. Concurrent, has a TUI, and works in CI.
- betterhook — A git hooks manager I built in Rust because existing ones don't handle worktrees or parallel agents well. DAG scheduling, blake3 caching, Tokio under the hood.
- rust-skills — 179 rules I wrote so AI coding agents stop guessing when they write Rust.
- LogRocket Blog — React, TypeScript, frontend architecture.
- Progress / Telerik Blog — React, Node.js, modern JavaScript.
