Decode and inspect JSON Web Tokens online free. View the JWT header, payload, and claims without your secret key — client-side only, no data sent anywhere.
This JWT decoder online free lets you inspect any JSON Web Token instantly, without needing your secret key. Paste the full header.payload.signature string and the tool immediately displays the decoded header and payload as formatted, readable JSON. When you need to decode JSON Web Token data to debug an authentication issue — checking whether the correct user ID is in the sub claim, verifying the exp (expiry) timestamp, or reading custom role and permission claims — this tool shows everything clearly with no setup required. As a JWT inspector online, it is particularly useful during API development: paste tokens from your auth server, Postman, or browser DevTools and read every claim in seconds. All decoding happens in your browser using standard Base64 decoding — nothing is sent to any server, making it safe to use with real production tokens. Note: this tool reads (decodes) the token contents only. It does not verify the signature or validate the token's authenticity.
The JWT Decoder parses a JSON Web Token and decodes its three Base64URL-encoded parts: the header, the payload, and the signature. JWTs consist of three dot-separated segments: Header.Payload.Signature. The header contains the algorithm (e.g. HS256, RS256) and token type. The payload contains the claims — data assertions such as user ID, expiry time (exp), issued-at (iat), and any custom application data. The signature verifies that the token was not tampered with. Our decoder reads the header and payload without needing the secret key, since those are only Base64-encoded (not encrypted). It also displays the expiry and issued-at timestamps in human-readable format and flags whether the token is expired.
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