I built 59 free browser-based dev tools in vanilla JS — here's what I learned

I've been quietly building Antigravity Tools — a collection of 59 free, browser-based developer utilities — and today I'm sharing everything I built and learned.

Why vanilla JS? No React, no build step.

The main constraint I set for myself: zero dependencies, zero server, zero telemetry.

When you paste your JWT token into jwt.io, it goes to their server. When you use an online regex tester, your test strings are logged. I built Antigravity Tools so every operation runs inside your browser, using native APIs.

No Node.js backend