Decode a JWT header and payload locally without sending the token to a server.
-Algorithm
-Expiration
-Token parts
For beginners: how to read the result
Start with the first cardIt gives the direct answer for the current mode before the longer output text.
Use the output boxCopy the exact converted value, table, header or parsed data from the output area.
Keep sensitive data localThe calculator runs in your browser, but you should still avoid secrets that your policy forbids in tools.
Paste your value, choose the mode if the calculator has one, and use the first result card as the direct answer. The longer output area is designed for copying into code, documentation, API tests or a spreadsheet.
What the result means
The output separates the header and payload JSON so claims such as alg, sub, iat and exp can be inspected quickly.
What is not included
The signature is not verified. Do not paste secrets or production tokens unless your own policy allows local browser inspection.
Privacy note
The interactive calculation runs in your browser. The page still should not be used with passwords, tokens or personal data that your own rules do not allow in browser tools.