JWT Decoder
Decode and inspect JSON Web Tokens (JWT) locally. View token headers, payload claims, and signatures instantly.
Decode and inspect JSON Web Tokens locally in your browser
How to use this tool
Zero Server Communication
Unlike web tools that post your tokens to a server, this JWT Decoder decodes everything locally in your browser memory. Your sensitive session tokens and payload details are 100% private.
How to Inspect a Token
Paste your token to parse the encoded header, payload claims, and signature attributes.
Paste Token
Paste the encoded JWT string. It typically has three base64 parts separated by dots (header.payload.signature).
Inspect Header
Verify the token type (typ) and the cryptographic signing algorithm (alg) used.
Inspect Payload
Analyze user attributes, roles, issue time (iat), and expiration time (exp) in standard JSON format.
Token Structure
JSON Web Tokens consist of three base64url-encoded parts:
Frequently Asked Questions
Quick answers about token encoding.
Does this decoder verify signatures?
This decoder splits and parses the token signature so you can inspect its raw base64 form. To verify the signature itself, you must validate it against your public key or shared secret, which is best done inside your secure backend.
Is my token data sent anywhere?
No. 100% of the token extraction, base64url decoding, and JSON formatting runs entirely in your local browser sandbox. No networks requests are made.
Privacy & Safety Policy
All tools run completely in your browser via client-side JavaScript. We do not upload your files, interest parameters, or JSON payloads to any server. Your data remains yours.