I spend a lot of time debugging things in production. Weird JSON responses, tokens that don't look right, timestamps that make no sense, hashes that need verifying.
Every time, it's the same thing — google "base64 decode online", paste sensitive production data into some random website, get the answer, move on. It always felt wrong.
So I built Stingr — a toolkit for the stuff I actually need during debugging. Everything runs in your browser, nothing gets sent anywhere. I made it together with Claude (yes, the AI —
we're friends now 🤖❤️) and figured I'd share it in case it helps you too.
👉 stingr.dev
The tools I actually use at 2am
JSON Tree Viewer — this is the one I built first and use most. When a production API returns a massive nested response and I need to find what's wrong, I need to expand/collapse by
depth, search for a specific field, pin the paths I keep checking. Recently added JSONPath queries too, so I can do $.data.users[*].errors and get just what I need.
JSON Compare — "why does staging return different data than prod?" Paste both, get a diff. It's smart enough to detect moved array items instead of marking everything as removed +
added.
JWT Decoder — "this token is supposed to have admin scope, does it?" One paste, header + payload + expiry right there.
Base64 / URL Decoder — some API just returned something encoded and I need to know what's in it. Fast.
Timestamp Converter — is this 1708531200 in seconds or milliseconds? What time is it actually?
Hash Generator & Verifier — quick SHA-256 checksums, HMAC verification, file integrity checks.
Key Case Converter — backend returns user_name but frontend expects userName? Convert all JSON keys with one click.
There's about 40 tools total — formatters, regex tester, cron parser, text diff, generators — but the ones above are my daily drivers.
Why it's all client-side
When I'm debugging production, I'm dealing with real user data. I don't want that going through someone else's server. Stingr runs 100% in the browser — open the Network tab and check,
zero requests. Hashing uses the Web Crypto API, everything else is plain JS.
How it's built
React + Vite, four dependencies total. Nothing fancy. I built it to solve my own problem and Claude helped me ship it way faster than I could have alone. Honestly a great experience
building together.
It's open source: github.com/yuval-atia/stinger
If it saves you even one "let me google base64 decode" during your next incident, I'm happy. And if you have ideas for tools you'd want — open an issue, I'm actively adding stuff.
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