JWT Decoder
Decode and inspect JSON Web Tokens (JWT) instantly
What is a JWT Decoder?
A JWT (JSON Web Token) Decoder is a tool that decodes and displays the contents of JWT tokens. JWTs are commonly used for authentication and authorization in web applications. Our decoder helps you inspect the header, payload, and signature of any JWT token without requiring server-side processing.
How to Use the JWT Decoder
- Copy your JWT token from your application or API response
- Paste the token into the input field
- The tool automatically decodes and displays the header, payload, and signature
- View token expiration status and common claims
- Copy individual sections (header, payload, or signature) as needed
- Use the sample token to see how JWT decoding works
Understanding JWT Structure
A JWT token consists of three parts separated by dots (.):
- Header: Contains token type (JWT) and signing algorithm (e.g., HS256, RS256)
- Payload: Contains claims (user data, permissions, expiration time)
- Signature: Ensures token integrity and authenticity
Common JWT Claims
- iss (Issuer): Who created and signed the token
- sub (Subject): The subject of the token (usually user ID)
- aud (Audience): Who the token is intended for
- exp (Expiration): When the token expires
- iat (Issued At): When the token was created
- nbf (Not Before): Token is not valid before this time
Benefits of Using Our JWT Decoder
- ✅ Instant JWT decoding without server requests
- ✅ View header, payload, and signature separately
- ✅ Automatic expiration checking
- ✅ Display common JWT claims in readable format
- ✅ Copy decoded sections with one click
- ✅ Client-side processing - your tokens stay private
- ✅ No registration or installation required
- ✅ Free and unlimited usage
Security Note
⚠️ Important: This tool only decodes JWT tokens - it does not verify signatures. JWT tokens are encoded (Base64), not encrypted. Anyone can decode a JWT and read its contents. Never store sensitive information in JWT payloads. Always verify JWT signatures on your server before trusting the token data.
Common Use Cases
- 🔍 Debugging authentication issues
- 👤 Inspecting user claims and permissions
- ⏰ Checking token expiration times
- 🔧 Testing JWT implementation
- 📊 Analyzing token structure
- 🎓 Learning about JWT tokens