A while back I shared some tiny browser-only tools I'd built to dodge ad-walls and "paste your data into our server" pages. I kept going — here are five more, all client-side, no signup, nothing uploaded.
Regex Tester
Live match highlighting, capture groups, a match count, and the g/i/m/s flags as toggles. Invalid patterns show the error instead of silently failing.
👉 https://tsetsobg.github.io/tools/regex-tester/
JWT Decoder
Paste a token, see the decoded header and payload with the expiry shown in a human-readable date (and flagged if expired). It decodes only — it doesn't pretend to verify the signature, and the token never leaves your tab.
👉 https://tsetsobg.github.io/tools/jwt-decoder/
SHA Hash Generator
SHA-256 / SHA-1 / SHA-512 of any text, live, via the Web Crypto API.
👉 https://tsetsobg.github.io/tools/hash-generator/
CSV ↔ JSON Converter
Both directions, with a proper CSV parser that handles quoted fields containing commas, escaped quotes and newlines (the usual thing that breaks naive split-on-comma converters).
👉 https://tsetsobg.github.io/tools/csv-to-json-converter/
Scientific Calculator
Order of operations, parentheses, powers/roots, trig, logs, π/e, degrees/radians — built on a small shunting-yard parser rather than eval, so it's safe to paste anything in.
👉 https://tsetsobg.github.io/tools/scientific-calculator/
Why offline / no-signup?
Each is a single static page with a small inline script — no backend, no account, no tracking in the hot path. Fast, works on a plane, and your input stays in the tab. The full set lives here: https://tsetsobg.github.io/tools/
What small dev utility do you keep re-googling? I'm still adding to the set and genuinely take requests.
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