Free Online JWT Debugger
Paste a JWT token to view its Header, Payload, and Signature and verify the expiration time. Parsed in your browser β the token never leaves your device.
Key Features
Three-part Parsing
Automatically splits the Header, Payload, and Signature and shows each part's raw content.
Base64 Decoding
Base64URL-decodes each part automatically and shows the readable JSON content.
Expiration Check
Detects the exp field and compares it with the current time to tell if the token is valid.
Local Parsing
The token is parsed entirely in the browser and is never uploaded to any server.
How to Use
Paste the Token
Copy the full JWT token from a request header or your code and paste it into the input box.
Auto Parse
Parsing happens automatically as you type β the three parts are displayed instantly.
Check Expiration
Inspect the exp field and expiration status in the payload to aid debugging.
Frequently Asked Questions
Can the JWT signature be decoded?
No. The JWT signature is the result of an HMAC over the first two parts using a secret key. The tool only decodes the Header and Payload; the signature cannot and should not be reversed.
Does this tool verify the signature?
No, because verification requires a server-side secret. This tool focuses on decoding content and viewing the expiration time for development and debugging. Perform real verification in your backend.
Will my token be uploaded?
No. Parsing happens entirely in the browser, and the token content never leaves your device. You can safely paste tokens from test environments.
Why does the decoded output look garbled?
If a part is not standard Base64URL encoding (for example, it contains invalid characters), it may show garbled text or fail to parse. Make sure you pasted the full JWT format.