regex101
regex101.com
Builds and explains a regular expression while you type it
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jwt.io
Decodes a JSON Web Token into readable header, claims and signature.
Paste a token and it splits into header, payload and signature with the claims formatted and the timestamps rendered as dates, so you can see straight away whether `exp` has passed or `aud` is wrong. Supply the secret or public key and it verifies the signature too. Decoding runs in the page rather than on their server, though pasting a live production token into any website is still a habit worth not forming.
AltFTool does this too
If you would rather not leave the site, JWT Decoder covers the same job here — free, no account, and it runs in your browser.
Open JWT DecoderQuestions
Works the moment the page loads. No account, no email, no trial. It decodes and verifies but is not a key manager — there is nowhere to store or rotate the keys you paste.
No. jwt.io does the work inside your browser, so the file never leaves your device — you can load the page, disconnect from the network, and it still works. That makes it a reasonable choice for material containing personal data.
It decodes and verifies but is not a key manager — there is nowhere to store or rotate the keys you paste.
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