I Built 47 Free Dev Tools That Run Entirely in Your Browser
Every developer has done it — copy-pasted a JWT, a private key, or a JSON blob with sensitive data into some random website and held their breath. Wondering if it was being logged, tracked, or worse. Every developer has done it — copy-pasted a JWT, a private key, or a JSON blob with sensitive data into some random website and held their breath. Wondering if it was being logged, tracked, or worse. I built KRUMB.DEV because I wanted tools that didn't make me feel dirty after using them. 46 develop
Every developer has done it — copy-pasted a JWT, a private key, or a JSON blob with sensitive data into some random website and held their breath. Wondering if it was being logged, tracked, or worse.
Every developer has done it — copy-pasted a JWT, a private key, or a JSON blob with sensitive data into some random website and held their breath. Wondering if it was being logged, tracked, or worse.
I built KRUMB.DEV because I wanted tools that didn't make me feel dirty after using them.
What Is It?
46 developer tools, all in one place. No signup. No uploads. No tracking. Open source.
The terminal-inspired interface isn't just aesthetic — it's a constraint. Every tool fits in a single column, zero sidebar, zero popups. Just you and the tool.
What's Inside
Formatters — JSON, SQL (17 dialects), HTML, JavaScript, CSS
Encoders — Base64, URL, JWT decoder, YAML↔JSON, JSON↔CSV
Generators — Passwords, UUIDs (v1/v3/v4/v5), hashes (MD5/SHA/HMAC), QR codes, Lorem Ipsum, color palettes, CSS gradients/shadows/grids, meta tags, robots.txt, .gitignore
Testing & Debugging — Regex tester, diff checker, webhook tester, cURL→code, HTTP status reference, cron expression builder
Converters — Unix timestamps, hex↔RGB, binary, SVG→JSX, JSON→TypeScript, HTML playground, markdown editor
Network — DNS lookup, SSL checker, IP lookup, QR code decoder, IBAN validator
Why I Built It This Way
Most "free" dev tools follow the same pattern: create an account, hit a rate limit, and wonder if your data is being stored somewhere.
KRUMB.DEV flips that:
- Everything runs in your browser — JSON, JWT, source code, passwords never touch a network request
- Zero accounts — open the page, use the tool, leave. No signup wall between you and the output
- Clean interface — ⌘K opens a command palette to jump to any tool in seconds
- Open source — MIT license, deploy your own if you want
The Tech
Next.js, TypeScript, and Tailwind. Static-first, client-side execution for all core tools. Server routes exist only for DNS/SSL lookups and webhook proxying — things that genuinely need a network call. Everything else is just your browser doing the work.
How to Use It
- Go to krumb-dev-five.vercel.app
- Press ⌘K and type the tool you need
- Paste your input, get your output, copy and move on
That's it. No onboarding flow, no "create an account to save", no "upgrade to remove ads".
What's Next
More tools, better tools. I'm working through a backlog of ideas based on what developers actually search for — SQL formatters, CSS generators, network debugging tools. The roadmap is driven by what's useful, not what monetizes.
Built by a developer, for developers. Star on GitHub if you find it useful.
