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JWT Inspector (Advanced)

Decode JWT header and payload. Note: Signature is NOT verified.

⚠️ Security Warning: This tool decodes JWTs without verifying signatures. Never trust decoded data without proper signature verification on the server side.

Header

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Payload

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Understanding JWT Algorithms:

  • HS256 (HMAC): Symmetric algorithm requiring a shared secret key. Fast and efficient.
  • RS256 (RSA): Asymmetric algorithm using public/private key pair. More secure for distributed systems.
  • ES256 (ECDSA): Elliptic curve digital signature algorithm. Similar to RSA but with smaller keys.
  • None: No signature (extremely insecure). Only use in development for testing.

JWT Decoder – Inspect and Decode JWT Tokens

JSON Web Tokens (JWTs) are widely used for authentication and authorization in modern web applications. JWTs contain encoded information in their header and payload that's useful for debugging, testing, and understanding token contents. The JWT Inspector (Advanced) by ToolfolioHub decodes JWT tokens to reveal header and payload information, helping developers understand and debug authentication tokens.

Important: This tool decodes JWTs without verifying signatures. Never trust decoded data without proper server-side signature verification.

What is a JWT?

JWTs consist of three parts separated by dots:

  • Header: Token metadata (algorithm, type)
  • Payload: Claims (user ID, expiration, permissions)
  • Signature: Cryptographic signature for verification

Format: `header.payload.signature`

What This Tool Does

The decoder:

  • Decodes Header: Shows algorithm and token type
  • Decodes Payload: Reveals claims (exp, iat, sub, etc.)
  • Analyzes Token: Checks expiration, algorithm, and structure
  • Does NOT Verify: Signature verification is not performed

Common JWT Claims

  • exp: Expiration timestamp
  • iat: Issued at timestamp
  • sub: Subject (usually user ID)
  • aud: Audience
  • iss: Issuer

Security Warning

This tool decodes tokens without signature verification:

  • Never Trust Decoded Data: Always verify signatures server-side
  • Use for Debugging Only: Educational and debugging purposes
  • Do Not Share Tokens: JWTs may contain sensitive information

Use-Cases

  • Debugging: Inspect token contents during development
  • Testing: Verify token structure and claims
  • Learning: Understand JWT structure and claims
  • Troubleshooting: Check expiration and token validity

Conclusion

The JWT Decoder is a valuable debugging tool for developers working with JWT authentication. By decoding tokens and analyzing their contents, it helps troubleshoot authentication issues and understand token structure. Remember: always verify signatures server-side in production.