JWT Debugger - Decode & Encode
Format, decode, and sign JSON Web Tokens (JWT) offline directly in your browser.
JWT Decode
Header (Decoded)ALGORITHM & TOKEN TYPE
{}Payload (Decoded)DATA / CLAIMS
{}JWT Encode
Alg:
Header (Editor)
Payload (Editor)
HS* HMAC Secret
Encoded Result TokenVERIFIABLE JWT STRING
JWT Debugger Online - Decode and Sign JSON Web Tokens
Analyze, format, decode, and sign JSON Web Tokens (JWT) online. Support symmetric and asymmetric algorithms (HMAC, RSA, ECDSA) 100% offline inside your browser.
Key Features
- Instant Decryption: Break down the structure of any token into its Header, Payload, and signature sections instantly.
- Real-time Encoding: Edit raw JSON values of Header/Payload and generate custom tokens signed with secure keys.
- Rich Cryptography Support: Supports HMAC (HS256, HS384, HS512), RSA (RS256, RS384, RS512), and ECDSA (ES256, ES384, ES512).
How to Debug JWTs
- To decode: Paste your JWT token into the left textarea.
- View the decoded Header and Payload instantly in the center column.
- To encode: Edit your JSON values in the editor panels on the right.
- Provide the signature key (Secret key or Private PEM file).
- Copy the newly signed token output from the "Encoded Result" panel.
Frequently Asked Questions (FAQs)
Is it safe to paste my JWT secrets here?
Yes, it is 100% safe. This is a local browser application. All token encoding/decoding is performed client-side using JavaScript, and no data is sent online.
Why does the debugger say 'Signature Invalid'?
A signature is invalid if the Secret Key or Asymmetric PEM Key provided in the signature panel does not match the key originally used to generate the token.