JWT Encoder & Decoder

JWT Encoder & Decoder Tool

Decode and inspect JSON Web Tokens (JWTs) to view their header, payload, and signature. Essential tool for developers working with authentication and authorization systems.

What is a JWT?

A JSON Web Token (JWT) is a compact, URL-safe means of representing claims to be transferred between two parties. JWTs are commonly used for authentication in web applications and APIs.

JWT Structure

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

• Header - Contains the token type (JWT) and signing algorithm (e.g., HS256, RS256)
• Payload - Contains the claims (user data, expiration time, etc.)
• Signature - Verifies the token hasn't been tampered with

Common Claims

• iss - Issuer (who created the token)
• sub - Subject (who the token is about)
• aud - Audience (who the token is intended for)
• exp - Expiration time (when the token expires)
• nbf - Not before (when the token becomes valid)
• iat - Issued at (when the token was created)
• jti - JWT ID (unique identifier)

Use Cases

• Debug authentication issues
• Inspect API tokens
• Verify token expiration
• Test JWT-based authentication
• Learn about JWT structure

Security Note

Warning: JWTs are signed, not encrypted. Do not include sensitive data in JWT payloads unless the token is encrypted. Anyone can decode a JWT and view its contents.

This tool decodes JWTs client-side in your browser. Your tokens are never sent to our servers.