Format, encode, decode and inspect data.
The developer tools are for the small data chores in between: formatting and validating JSON, encoding and decoding Base64 and URLs, reading what's inside a JWT, making MD5 and SHA hashes of text or files, and testing JavaScript regular expressions against sample text.
Paste your input and the result updates as you type, ready to copy. JSON errors point to the line and column, so a broken payload is quick to fix.
No. It decodes the token so you can read its header, claims and expiry, but it doesn't verify the signature. Only your server, with the secret or public key, can confirm a token is genuine.
SHA-256 for anything new: it's the standard for checksums and signatures. MD5 and SHA-1 are broken for security, but still fine for spotting accidental corruption or matching older systems.
It shows exactly where the JSON breaks, by line and column, so you can correct it. The usual causes are single quotes, trailing commas and comments, which JavaScript allows but JSON doesn't.