JWT Decoder
Decode a JWT header & payload (signature not verified).
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About JWT Decoder
The JWT Decoder splits a JSON Web Token into its parts and decodes the Base64Url header and payload into pretty-printed JSON, so you can inspect the algorithm, token type and every claim without hunting for a library. It is a decoder only: the signature is deliberately not verified, and no secret or public key is ever requested.
Timestamp claims get special treatment. When the payload contains iat (issued at), exp (expires) or nbf (not before), the tool converts each one into a readable UTC date — the quickest way to answer the eternal question of whether a token has actually expired.
Paste the full header.payload.signature string and the decoder handles the rest, including tokens whose payload is not strict JSON. Malformed input — fewer than two segments, or invalid Base64Url — produces a clear error instead of silently garbled output.
How to use JWT Decoder
- Paste the complete JWT — the header.payload.signature string — into the token field.
- Run the decoder.
- Read the decoded header (algorithm, type) and the payload claims as formatted JSON.
- Check the DATES section for the human-readable iat, exp and nbf timestamps.
- Copy the output for your bug report or debugging notes.