JWT Decoder
Paste a JWT token to decode and inspect its header, payload, and signature.
What is a JWT?
A JSON Web Token (JWT) is a compact, URL-safe token format used for securely transmitting information between parties. It consists of three Base64url-encoded parts separated by dots: a header (algorithm and token type), a payload (claims such as user ID, expiration, and roles), and a signature (used to verify the token has not been tampered with).
How to Use This Tool
- Paste your JWT token into the input field.
- Click Decode to view the header, payload, and signature.
- Each section is pretty-printed as formatted JSON.
- Click Copy on any section to copy it to your clipboard.
- If the token is invalid, an error message will explain what went wrong.
Features
- Decode JWT header and payload to pretty-printed JSON
- Display the raw signature string
- Copy individual sections to clipboard
- Clear error messages for malformed tokens
- Works entirely in your browser — no data is sent to any server
Important Note
This tool decodes JWTs but does not verify signatures. Never paste production tokens containing sensitive data into any online tool. This decoder runs entirely client-side and never transmits your token.