JWT Token Decoder

A JWT decoder (JSON Web Token decoder) is an essential tool for developers working with OAuth authentication and API security. JWT tokens are encoded strings that contain user identity and permission data, used by modern APIs for authentication and authorization.

The Problem: Debugging OAuth Authentication

When integrating with APIs that use OAuth 2.0 or OpenID Connect, you receive access tokens and ID tokens that look like random strings. Without a JWT debugger, you can't see what's inside these tokens—making it difficult to troubleshoot authentication issues or understand what permissions are granted.

• OAuth tokens appear as unreadable encoded strings
• Authentication failures are hard to debug without seeing claims
• Token expiration issues go unnoticed until runtime
• Understanding granted scopes requires decoding

The Solution: Free Online JWT Decoder

This free JWT token decoder instantly decodes any JWT and shows you the header, payload, and claims in a readable format. See the algorithm used, expiration time, user information, and any custom claims—all without sending your sensitive tokens to any server.

Understanding JWT Token Structure

Every JWT consists of three parts separated by dots: the header, payload, and signature. This JWT parser decodes each section:

• Header - Contains the algorithm (HS256, RS256, etc.) and token type
• Payload - Contains claims like user ID, email, roles, and expiration
• Signature - Verifies the token hasn't been tampered with

Common JWT Claims Explained

• iss (Issuer) - The authentication server that created the token
• sub (Subject) - The user ID or identifier the token represents
• aud (Audience) - The intended recipient (your application)
• exp (Expiration) - When the token expires (Unix timestamp)
• iat (Issued At) - When the token was created
• scope - The permissions granted by this token

Perfect for n8n OAuth Integration

When building n8n automation workflows that connect to OAuth-protected APIs, you often need to debug authentication issues. This OAuth token decoder helps you:

• Verify access tokens from OAuth2 credential nodes
• Check token expiration before making API calls
• Debug authentication failures in HTTP Request nodes
• Understand what scopes and permissions are granted
• Extract user information from ID tokens

Why Choose This JWT Decoder?

• 100% Client-Side - Your tokens never leave your browser
• Free Forever - No sign-up or usage limits
• Expiration Check - Instantly see if your token is expired
• Readable Format - Claims displayed in an easy-to-read table
• Timestamp Conversion - Unix timestamps automatically converted to dates