JWT Decoder

Decode and inspect JSON Web Tokens quickly, securely, and privately—right in your browser.

Use our free JWT Decoder to quickly decode, inspect, and troubleshoot JSON Web Tokens (JWTs). Just paste your token above to view its header and payload in plain, readable format. All decoding happens locally in your browser to ensure absolute privacy—your tokens never leave your device. Perfect for developers, security researchers, and anyone working with JWTs in authentication or authorization systems.

Decode Your JWT Online

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Decoded JWT Header
Decoded JWT Payload
JWT Signature
Need more JWT tools? Try our JWT Creator to generate tokens, or JWT Verifier to check token validity and signatures.

What is a JSON Web Token (JWT)?

A JWT is a compact, URL-safe token for securely transmitting information as a JSON object between parties.

A JWT is a standard way to securely transmit data as signed JSON objects.

A JWT has three parts: header (specifies type and algorithm), payload (contains claims), and signature (verifies integrity).

  • JWT Header: Contains the signing algorithm and token type.
  • JWT Payload: Includes claims—user info, roles, or session data.
  • JWT Signature: Ensures the token is authentic and hasn’t been altered.

How JWTs Work

JWTs provide authentication by storing tokens client-side and validating the signature on each request.

  1. When a user logs in, the server creates a signed JWT.
  2. The JWT is sent to the user and stored securely (usually in local storage or cookies).
  3. The client includes the JWT in every request to protected routes.
  4. The server checks the JWT’s signature to grant or deny access.

Popular JWT Use Cases

JWTs make authentication and secure data exchange simple and efficient:

  • User login authentication for websites and apps.
  • Securing API endpoints and managing access tokens.
  • Handling identity tokens in OAuth2 and OpenID Connect flows.
  • Protecting applications from CSRF attacks with stateless tokens.
  • Safely transmitting custom user or session data in claims.

JWT Privacy & Security

To keep your JWTs secure, always follow these best practices:

  • Always validate JWT signatures before trusting the payload.
  • Never use weak or insecure algorithms like 'none' for JWTs.
  • Set appropriate expiration times to minimize risk from leakage.
  • Store JWTs securely (prefer HttpOnly cookies over localStorage).
  • Leverage audience claims (aud) to restrict token usage.
  • Implement ways to revoke tokens or use short lifespans.

JWT Reference Resources