JWT Decoder & Debugger

Decode and verify JSON Web Tokens (JWT) instantly in your browser. All processing happens locally - your tokens never leave your device.

Encoded JWT

What is JWT?

JSON Web Token (JWT) is an open standard (RFC 7519) that defines a compact and self-contained way for securely transmitting information between parties as a JSON object. This information can be verified and trusted because it is digitally signed.

JWT Structure

A JWT consists of three parts separated by dots (.):

  • Header: Contains the token type and signing algorithm
  • Payload: Contains the claims (statements about an entity)
  • Signature: Used to verify the sender and ensure the message wasn't changed

Common Use Cases

  • Authentication: Most common use case. Once logged in, each request includes a JWT
  • Information Exchange: Securely transmit information between parties
  • Authorization: Determine user permissions and access levels

Security Best Practices

  • Always use HTTPS when transmitting JWTs
  • Keep your secret keys secure and never commit them to version control
  • Set appropriate expiration times (exp claim)
  • Use strong signing algorithms (HS256, RS256)
  • Validate tokens on every request
  • Don't store sensitive information in JWT payload (it's not encrypted, only encoded)