My JWT decoder says the token is invalid JSON

One of the first two segments is not valid Base64URL-decoded JSON. Check for a truncated token, an extra quote, or a token format that is not actually JWT.

The payload won't decode in another Base64 tool

JWTs use Base64URL, not standard Base64. `-` and `_` replace `+` and `/`, and padding is often omitted.

The token looks readable but my API still rejects it

Decoding is not verification. The signature may be wrong, the issuer may be untrusted, the audience may not match, or the token may be outside its `nbf` / `exp` window.

`exp` looks like a random number

It's usually a Unix timestamp in seconds. `1712592000` is a date, not a duration.

Can I decode JWT token locally without uploading it?

Yes. This tool runs in the browser, so the token can be inspected locally instead of being sent to a remote decoder service.

JWT Decoder & Inspector

Decode JWT header and payload locally, inspect common claims, and review token timing metadata.

Decode only

This tool decodes JWT contents locally but does not verify the signature or trustworthiness of the token.