Tools
Small things I reach for most days. They run entirely in your browser — nothing you paste is transmitted anywhere, which is mostly why they exist.
JWT decoder
Decode a JSON Web Token and read its claims, with timestamps as dates and expiry stated plainly. Decodes only — it does not verify the signature.
jwt · jsonwebtoken · bearer · token · claims
UUID generator
Generate version 4 UUIDs from the browser’s cryptographic random source, in whatever quantity and formatting you need.
uuid · guid · v4 · identifier · random
Text power tools
Paste plain text and clean it up — remove empty or duplicate lines, join, trim, sort, reverse, change case. Operations combine, and everything is undoable.
text · lines · dedupe · duplicate · trim
URL and HTML codec
Percent-encoding and HTML entities, both directions — with the difference between escaping a whole URL and escaping one component made explicit rather than guessed.
url · uri · percent · encode · decode
JSON and YAML formatter
Paste either and get it formatted. The format is worked out from the input, said out loud, and overridable when the guess is wrong — and each can be rendered as the other.
json · yaml · yml · format · prettify
Text diff
Compare two texts line by line and see exactly what changed, with whitespace and case differences ignorable when they are not the point.
diff · compare · difference · changes · text
Cron expression parser
Read a cron expression in plain English, see when it next runs, and convert between the five-field and six-field forms — including the day-of-month and day-of-week rule most parsers get wrong.
cron · crontab · schedule · quartz · spring
Unix timestamp converter
Turn a Unix timestamp into a date or a date into a timestamp, with the unit it assumed and the way it read your input both stated rather than guessed at silently.
unix · timestamp · epoch · date · time
Hashes and base64
Base64 and base64url in both directions, and SHA-256, SHA-384 and SHA-512 digests as hex or base64 — computed by the browser, with decoding failures explained rather than thrown.
base64 · base64url · encode · decode · hash
Image metadata stripper
See what your photographs are carrying — GPS coordinates, camera, date, software — and remove it. JPEG and PNG are rewritten without re-encoding, so the picture itself is untouched.
exif · metadata · gps · location · privacy
Image file size reducer
Resize and re-encode photographs to something a web page can carry, with the original and the result side by side so the trade-off is visible before you save it.
image · compress · resize · shrink · optimise
Network toolkit
Subnet and address arithmetic, what your browser actually measured about this connection, and the exact ping, traceroute and dig command for your platform — since a browser cannot run those itself.
network · ping · traceroute · tracert · dns