JWT Decoder - Parse JSON Web Tokens
Instantly decode the payload and header of your JSON Web Tokens (JWT). Our JWT Decoder extracts the claims inside your token securely, ensuring your sensitive authentication data never leaves your browser.
What is a JWT Decoder?
A JSON Web Token (JWT) is a standard method for securely transmitting information between parties as a JSON object, heavily used in modern authentication systems. However, the token itself is Base64Url encoded, making it unreadable to humans. The JWT Decoder takes your token string and decodes the Header (algorithm and token type) and the Payload (the actual user data or claims). Crucially, this tool operates entirely client-side. We know JWTs often contain sensitive authorization data, so our tool guarantees that your token is never sent to a server.
Why Use Our JWT Decoder?
- Instant Decoding: Instantly view the decoded JSON payload and header.
- 100% Secure: Your authentication tokens are processed locally and never logged.
- Developer Friendly: Formats the JSON output for easy readability.
- Offline Capable: Works even without an internet connection once loaded.
How to Use the JWT Decoder
Paste your encoded JSON Web Token (JWT) into the input box.
The tool automatically detects the token structure (header.payload.signature).
View the beautifully formatted JSON header and payload below.
Analyze the claims (like user ID or expiration time) for debugging.
Frequently Asked Questions
No, this tool only decodes the Base64Url encoded payload and header. It does not validate the cryptographic signature.
Yes. The decoding happens entirely via JavaScript in your local browser. We have no backend server that logs or stores your tokens.
This tool is strictly a decoder. To edit a payload and create a valid token, you would need to re-sign it with your private server key.
All file processing is performed locally in your web browser. We do not upload, store, or view your data.