JWT Decoder
Decode and inspect JSON Web Tokens (JWT) instantly in your browser.
All processing happens in your browser. Your data never leaves your device.Features
- Decode JWT header and payload with formatted JSON output
- Display signature information and algorithm used
- Show token expiration status with human-readable dates
- Detect and display standard JWT claims (iss, sub, aud, exp, iat, nbf)
- Real-time decoding as you paste — no submit button needed
How to Use the JWT Decoder
- 1Paste your JWT token (starting with eyJ...) into the input area
- 2The header, payload, and signature are decoded and displayed instantly
- 3Check the expiration status — active tokens show green, expired show red
- 4Click "Copy" to copy any section to your clipboard
Frequently Asked Questions
What is a JWT (JSON Web Token)?
A JWT is a compact, URL-safe token format used for securely transmitting information between parties. It consists of three parts separated by dots: a header (algorithm and token type), a payload (claims/data), and a signature. JWTs are commonly used for authentication and authorization in web applications.
Is it safe to decode JWTs here?
Yes. JWT decoding is done entirely in your browser using JavaScript's atob() function. Your token is never sent to any server. Note that decoding a JWT does not verify its signature — it only reads the data contained within.
Does this tool verify JWT signatures?
No. This tool decodes and displays the content of JWT tokens but does not verify signatures. Signature verification requires the secret key or public key used to sign the token. Use this tool for inspecting token contents during development and debugging.