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A JWT parser splits a compact token at the two dots, Base64URL-decodes the header and payload, and shows each as pretty-printed JSON alongside the raw signature bytes. The goal is structural: see what algorithm the header claims, which claims the payload actually carries, and how long the signature is. This tool never calls a network; parsing is local so you can paste production tokens without leaking them.
Paste a token from a new partner integration and immediately see which claims they populate and what algorithm they sign with.
Mobile clients sometimes cap header size; parsing tells you which claim is responsible for a bloated token.
Some services use custom claim names. The parser exposes them so your verifier can match the exact keys.
After your code signs a token, parse it to confirm the header and payload look exactly like the spec expects.
No. Parsing is structural only. Use a dedicated verifier with the right public key when signature validation matters.
Only unencrypted JWS tokens are parsed. JWE tokens with five dot-separated parts need decryption before anything meaningful is visible.
The signature is Base64URL-decoded to bytes and its length is shown; the raw bytes themselves are rarely useful without the key.
Either the three parts are not present or one is not valid Base64URL. Check that you copied the whole token including both dots.