JWT Decoder
Decode and verify JSON Web Tokens with header and payload inspection
JWT Token Input
JWT Token
Decoded JWT
Paste a JWT token above to decode it
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A JWT (JSON Web Token) Decoder is an essential tool for developers working with modern authentication systems. JWTs are self-contained tokens that carry information about a user or system in a compact, URL-safe format. Our JWT Decoder allows you to instantly parse and inspect any JWT token to understand its structure, claims, and metadata. The tool breaks down the three parts of a JWT: the header (containing algorithm and token type), the payload (containing claims and user data), and the signature (used for verification). This decoder is invaluable for debugging authentication flows, understanding token contents, verifying claim structures, and troubleshooting authorization issues in web applications, mobile apps, and API integrations. It supports all standard JWT formats and provides detailed information about token expiration, issuer, audience, and custom claims.
When to Use JWT Decoder
Use our JWT Decoder whenever you need to inspect the contents of a JWT token during development, debugging, or security analysis. This tool is particularly useful when troubleshooting authentication issues in single-page applications, mobile apps, or API services. Developers commonly use it to verify that tokens contain the expected user information, check expiration times, validate claim structures, and understand how their authentication system is packaging user data. It's essential when integrating third-party authentication services like Auth0, Firebase, or AWS Cognito, as you can decode tokens to ensure they contain the required claims. The tool is also valuable during security audits to analyze what information is being transmitted in tokens and whether sensitive data is properly protected.
How to Use JWT Decoder
7 stepsCopy the JWT token from your application, browser developer tools, or API response
Paste the complete JWT token into the decoder input field
The tool automatically parses the token and displays its three sections
Review the header section to see the signing algorithm and token type
Examine the payload section to inspect all claims and user data
Check the expiration time and other timestamp claims for validity
Copy specific claims or the entire decoded content as needed for debugging
Privacy & Security
100% SecureYour JWT tokens are processed entirely within your web browser using client-side JavaScript technology. No token data is ever transmitted to our servers, stored, or logged anywhere outside your device. This ensures complete privacy and security for sensitive authentication information, user data, and proprietary claims. The tool works offline once loaded, providing an additional layer of security for confidential JWT analysis and debugging.
Pro Tips
7 tipsAlways verify the 'exp' (expiration) claim to ensure tokens are still valid for your use case
Check the 'iss' (issuer) claim to confirm tokens are coming from your expected authentication provider
Look for custom claims that contain user roles, permissions, or other application-specific data
Compare the 'iat' (issued at) time with your server logs to debug timing issues
Use the decoded payload to understand what user information is available without additional API calls
Validate that sensitive information isn't exposed in JWT claims, as they're only encoded, not encrypted
Keep decoded token information secure and don't share it in screenshots or documentation
Frequently Asked Questions
5 Q&AQ1:What is a JWT token and why would I need to decode it?
JWT (JSON Web Token) is a compact, URL-safe means of representing claims between two parties. You need to decode JWTs to inspect user information, verify token structure, debug authentication issues, and understand what data is being transmitted in your application's authentication system.
Q2:Is it safe to decode JWT tokens with this tool?
Yes, our JWT decoder processes tokens entirely within your browser using client-side JavaScript. Your JWT tokens never leave your device or get sent to our servers, ensuring complete security for sensitive authentication data.
Q3:Can this tool verify JWT signatures?
This decoder focuses on parsing and displaying JWT structure and claims. For signature verification, you'll need the secret key or public key used to sign the token. We recommend using our JWT Verifier tool for signature validation with your keys.
Q4:What information can I see in a decoded JWT?
When decoded, you'll see the header (algorithm and token type), payload (claims like user ID, expiration time, issuer), and signature section. The tool displays all standard claims (iss, aud, sub, exp, iat) and any custom claims in an easy-to-read format.
Q5:Why does my JWT token show as expired?
JWT tokens include an 'exp' (expiration) claim that specifies when the token expires. Our decoder automatically checks this timestamp against the current time and warns you if the token has expired, helping you debug authentication timing issues.
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