About JWT Decoder
Decode and inspect JWT tokens instantly with our free JWT decoder. View header, payload, claims, and check expiration status with syntax highlighting and validation.
Key Features
- 🔍 Instant Decoding: Decode JWT tokens in real-time
- 📋 Three-Part View: Header, payload, and signature sections
- 🎨 Syntax Highlighting: JSON syntax highlighting for better readability
- ⏰ Expiration Check: Automatic expiration status validation
- 🔒 Claims Analysis: Detailed breakdown of JWT claims
- 📱 Mobile Optimized: Works perfectly on all devices
- 🔒 100% Private: All processing happens in your browser
What is JWT?
JSON Web Token (JWT) is an open standard (RFC 7519) that defines a compact and self-contained way for securely transmitting information between parties as a JSON object. JWTs are commonly used for authentication and information exchange in web applications.
JWT Structure
🔗 Three Parts of JWT
1. Header:
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9Contains algorithm and token type
2. Payload:
eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQContains claims and user data
3. Signature:
SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5cVerifies token integrity
Common JWT Claims
📋 Standard Claims
- iss: Issuer (who created the token)
- sub: Subject (user identifier)
- aud: Audience (intended recipient)
- exp: Expiration time
- iat: Issued at time
- nbf: Not before time
🔧 Custom Claims
- name: User's full name
- email: User's email address
- role: User's role or permissions
- scope: Access scope
- groups: User groups
- custom: Application-specific data
Common Use Cases
🔐 Authentication
- • User login sessions
- • Single Sign-On (SSO)
- • API authentication
- • Mobile app authentication
📊 Information Exchange
- • Secure data transmission
- • Microservices communication
- • Third-party integrations
- • Stateless applications
🛠️ Development & Debugging
- • Token inspection
- • Debugging authentication issues
- • Validating token structure
- • Testing JWT implementations
🔍 Security Analysis
- • Token expiration checking
- • Claims validation
- • Security auditing
- • Compliance verification
JWT Security Considerations
- 🔐 Signature Verification: Always verify JWT signatures in production
- ⏰ Expiration Handling: Check and handle token expiration properly
- 🔒 Secure Storage: Store JWTs securely (httpOnly cookies recommended)
- 🚫 Sensitive Data: Don't include sensitive data in JWT payload
- 🔄 Token Rotation: Implement token refresh mechanisms
- 🛡️ Algorithm Validation: Validate the algorithm used for signing
Supported Algorithms
🔐 HMAC
- • HS256 (HMAC SHA-256)
- • HS384 (HMAC SHA-384)
- • HS512 (HMAC SHA-512)
🔑 RSA
- • RS256 (RSA SHA-256)
- • RS384 (RSA SHA-384)
- • RS512 (RSA SHA-512)
📈 ECDSA
- • ES256 (ECDSA SHA-256)
- • ES384 (ECDSA SHA-384)
- • ES512 (ECDSA SHA-512)
Frequently Asked Questions
What is a JWT (JSON Web Token)?
JWT is an open standard (RFC 7519) that defines a compact and self-contained way for securely transmitting information between parties as a JSON object. It is widely used for authentication and authorization in modern web applications.
Is this JWT decoder secure?
Yes, our JWT decoder works entirely on the client side. Your token is never sent to our servers; it is decoded directly in your browser, ensuring that your sensitive authentication data remains private.
Can this tool verify the signature of my JWT?
This tool is a decoder and debugger that allows you to inspect the contents of a JWT. It does not perform signature verification against a secret key, as that should only be done in a secure server-side environment.
How can I check if my JWT has expired?
Once you paste your token, look at the 'Payload' section. Our tool automatically interprets the 'exp' (expiration) claim and displays a human-readable status telling you if the token is active or expired.
What are the three parts of a JWT?
A JWT consists of three parts separated by dots (.): 1) The Header (specifies the algorithm), 2) The Payload (contains the claims/data), and 3) The Signature (verifies the integrity of the token).
How to Use
- Paste your JWT token into the input field
- The token will be automatically decoded and displayed
- View the header, payload, and signature sections
- Check the expiration status and claims
- Use the decoded information for debugging or analysis
Privacy & Security
- 🔒 Local Processing: All decoding happens in your browser
- 🚫 No Data Transmission: Your JWT tokens never leave your device
- 🗑️ No Storage: We don't store your tokens or decoded data
- ⚡ Offline Capable: Works without internet connection