JWT Decoder β read header & payload
Decode a JWT header and payload in your browser. No data leaves your device.
π Runs entirely in your browser. Your input and output are never sent to a server or stored β fully private.
π Decoded in your browser. The signature is NOT verified.
About this tool
This JWT decoder splits a JSON Web Token into its three parts and shows the decoded header and payload as readable JSON, including claims such as the issuer, subject and expiry. Paste a token to inspect what it contains while debugging authentication or APIs. The decoding happens entirely in your browser, so your tokens are never transmitted or stored.
Frequently asked questions
What is inside a JWT?
A JWT has three Base64URL-encoded parts separated by dots: a header describing the signing algorithm, a payload of claims (data such as user ID and expiry), and a signature. This tool reads the header and payload; the dot-separated structure is what makes a token decodable without a key.
Does this verify the token signature?
No. This tool only decodes the header and payload so you can read them β it does not verify the signature or check that the token is authentic. Anyone can read a JWT, so never put secrets in the payload and always verify signatures on your server.
Is my token sent anywhere?
No. The token is decoded entirely in your browser and is never sent to or stored on a server, which is important because tokens often grant access to accounts.