Some of what you see here is sample content. While the community forms, part of the members, reviews, ratings and discussions are seeded examples. Every one is badged Sample, and they do count towards the totals on this site. Vendor pages, the security data and the tools are real.
JWT decoder
Reads the header and claims of a token so you can see what it asserts and when it dies. Decoding happens in this tab and the token is never put in the URL, because a JWT in a browser history or a referrer header is a credential you have handed away.
Everything you type stays in this tab. Share copies a link, never your inputs, unless the tool says it encodes them in the URL.
Header
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Claims
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This does not verify the signature, and nothing that decodes a token in a browser can. Verification needs the issuer's key and a library that checks the algorithm against what you expect. A token that decodes cleanly is not a token that is valid.