A JWT's header and payload are often readable after decoding, but readable claims are not automatically trustworthy. Before using a JWT decoder, confirm that you are allowed to inspect the token and understand where the tool processes input. Prefer a synthetic token when asking for help.
You can inspect fields such as issuer, audience, subject, and expiration to diagnose a problem. To trust those fields, an application must validate the signature with the expected algorithm and key, as well as relevant claims and time constraints. Decoding alone does none of that.
Never post a live bearer token; anyone who obtains it may be able to use it until it expires or is revoked.
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