How to Decode JWT Tokens Securely

JWT (JSON Web Tokens) are widely used for authentication and authorization in modern web applications. Understanding how to decode and inspect JWTs is crucial for developers working with APIs and authentication systems.

What is a JWT?

A JWT is a compact, URL-safe token that consists of three parts separated by dots:

• Header: Contains token type and signing algorithm
• Payload: Contains claims (user data, permissions, etc.)
• Signature: Used to verify the token's authenticity

Decoding JWTs Safely

Important: Decoding a JWT only reveals its contents - it doesn't verify the signature. Always verify tokens on the server side.

Using Our JWT Decoder

1. Paste your JWT token into the input field
2. The tool automatically decodes the header and payload
3. View claims, expiry status, and token information
4. Edit and regenerate tokens for testing

Understanding JWT Claims

Common claims you'll find in JWTs:

• iss (Issuer): Who issued the token
• sub (Subject): The user ID or subject
• exp (Expiration): When the token expires
• iat (Issued At): When the token was issued
• aud (Audience): Intended recipient

Security Best Practices

• Never store sensitive data in JWT payloads
• Always verify signatures on the server
• Use HTTPS to prevent token interception
• Set appropriate expiration times
• Validate all claims before trusting the token

Common Use Cases

• Debugging authentication issues
• Inspecting token contents during development
• Understanding API authentication
• Testing token generation

Try our JWT Decoder tool to decode and inspect your tokens safely!