Matheus Cardoso
Software Engineer at 4Selet
I'm a software engineer at 4Selet and Zero7, where I build payments: checkout, billing and payouts. I want paying to feel invisible to the person buying.
I made Craft, a course on interface details, and Régua, a tool to measure and annotate any live interface. The open source I'm proudest of is Abacate Pay, built by 23 devs. Before that I worked with Goiás F.C. and a few others. I run every day and make a playlist every month.
You can reach me at @mattcrdoso and via email or see my code on GitHub.
Projects
Contributions
Skills
- Language
- TypeScriptJavaScriptPHPRubyDartJavaSQL
- Frontend
- AngularRxJSNgRxReactNext.jsFlutterTailwind CSSshadcn/uiAlpine.jsBootstrapjQuery
- Backend
- LaravelNestJSNode.jsRuby on RailsQuarkusPrisma
Writing
- 2026Twenty-two, each with an example
The skills I use every day
New - Three ways to run an agent
Loops, harnesses and graphs
- Five free repos, months saved
5 GitHub repos that give you an unfair advantage in AI
- Why the bubble will burst
AI is close to breaking. Here's why.
- Buttons and lists on WhatsApp
Interactive messages with the WhatsApp Cloud API
- Spend fewer tokens, ship more
How to save Claude Code tokens
- A better color space for UI
What are OKLCH colors?
- What nobody notices, but feels
Invisible details
Crafts
Components I build and drop here, one at a time.
Command Palette with Argument Chips
Commands that take their arguments inline, collapse into chips, and a list that measures itself before changing height.
Loading State
A pixel-grid loader, with a shimmer across the label and the time elapsed.
Cassette Audio Player
An audio player built into a compact cassette.