JWT Decoder — Decode JSON Web Tokens Instantly

Use our JWT Decoder to decode any JSON Web Token (JWT) safely in your browser. View the Header, Payload, and Claims in beautifully formatted JSON — perfect for debugging authentication, validating tokens, or analyzing API responses.

Example JWT

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiYWRtaW4iOnRydWUsImlhdCI6MTUxNjIzOTAyMn0.KMUFsIDTnFmyG3nMiGM6H9FNFUROf3wh7SmqJp-QV30

Decode Your JWT

Understanding JSON Web Tokens (JWT)

This guide explains what JSON Web Tokens (JWT) are, how they work, and why they are widely used for modern authentication, API security, and stateless session handling. JWT is a compact and URL-safe way to transmit signed information between a client and server.

What is JWT?

A JSON Web Token (JWT) is an industry-standard token format (RFC 7519) used to securely transmit identity and claims data between parties. JWTs are popular in login systems, API access, single sign-on (SSO), and microservices authentication.

How Does a JWT Work?

A JWT is composed of three Base64URL-encoded parts, separated by dots:

  • Header: Specifies the token type (JWT) and the signing algorithm (HS256, RS256, etc.).
  • Payload: Contains claims such as user ID, expiration time, roles, and other metadata.
  • Signature: Ensures the token is valid and unaltered. Created using the encoded header + payload + a secret key.

A typical JWT looks like this:


eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.
eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.
SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

Why Use JWT?

  • Compact: Small enough to send via URL, headers, or cookies.
  • Self-contained: Includes all required user details inside the token.
  • Secure: Signed using HMAC or RSA/ECDSA — prevents tampering.
  • Stateless: The server does not need session storage. Great for scalable APIs.
  • Fast: Efficient for microservices, serverless functions, and edge systems.

JWT Authentication Flow (Example)

Here's how a typical JWT login system works:


1. User logs in with email + password.
2. Server validates credentials.
3. Server generates a signed JWT token.
4. JWT is returned to the client (browser/app).
5. Client stores token (LocalStorage, Secure Cookie, etc.).
6. For each request, client sends JWT in Authorization header:
   Authorization: Bearer <token>
7. Server verifies the token and grants access.