Errors

JWT Decoder and Signature Verifier Troubleshooting

Common issues and troubleshooting notes for the jwt decoder and signature verifier.

Page Summary

Paste a JWT to review its header and payload, inspect claim values and optionally verify HS256, HS384 or HS512 signatures with a local secret.

Use the troubleshooting notes below to identify common mistakes and fix them quickly.

Common Issues

Error 1

A valid JWT must contain three sections separated by dots.

Error 2

If the token payload is not valid Base64URL, the decoder cannot read it correctly.

Error 3

Verification fails when the secret or selected algorithm does not match the token signature.

JWT Inspection Workflow

Paste a JWT to review its header and payload, inspect claim values and optionally verify HS256, HS384 or HS512 signatures with a local secret.

Use the troubleshooting notes below to identify common mistakes and fix them quickly.

JWT Inspection Workflow

Paste a JWT to review its header and payload, inspect claim values and optionally verify HS256, HS384 or HS512 signatures with a local secret.

Frequently Asked Questions

Does this tool upload my JWT token?

No. JWT decoding and HMAC-based verification are performed in the browser during normal use.

Which signature algorithms are supported?

This page supports HS256, HS384 and HS512 verification for HMAC-based JWT tokens.

Can I review exp, iat and nbf as readable dates?

Yes. Standard JWT time claims are converted into easier-to-read date and time values.