Picture the last time you needed to decode a JWT. You Googled "jwt decoder," clicked the first result, and pasted in a token — often a live one — into a text box on a server you know nothing about.
That moment bugged me for years. So I built DevTools Kit: 30 everyday developer utilities that do all their work inside your browser. Nothing you paste is ever sent anywhere. No sign-up, no ads, no analytics watching you.
The one rule: your data never leaves your machine
This is the whole reason the project exists. When you paste a JWT, an API response, or a chunk of production SQL into most online tools, that data hits someone else's backend. DevTools Kit runs every operation client-side. Don't take my word for it — open the page, kill your network connection, and every tool still works.
What's inside
Formatters — JSON, XML, HTML, CSS, SQL
Converters — Base64, URL, HTML entities, YAML ↔ JSON, CSV ↔ JSON, JSON → TypeScript
Decoders — JWT decoder, Base64, URL
Generators — UUID, Lorem Ipsum, hashes, Unix timestamps
And the one I'm most proud of:
Code Compare — a real side-by-side diff. Most online diff tools print one merged column, so a single changed character shows up as a whole line deleted plus a whole line added — useless for source code. Code Compare aligns the two versions in parallel columns and highlights only the characters that actually changed.
How it's built
- Vue 3 for the interface
- Server-side rendered at build time — every tool is a static HTML page, so it loads instantly and works even with JavaScript disabled
- Cloudflare Pages on the edge
- Lighthouse: 100 Performance, 100 SEO, 100 Best Practices
It's free, and there's nothing to sign up for
If it stops you from pasting one sensitive token into a sketchy site, it's done its job.
👉 Try it: devtoolskit.uvercy.com
Now I'm curious: what's a tool you keep using online that you wish ran locally instead? Drop it in the comments — I'm actively adding tools and yours might be next.
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