JWT Decoder
Decode and analyze JSON Web Tokens for debugging and security
All JWT processing happens in your browser only. Never paste production tokens with sensitive data. This tool is for development and debugging purposes.
JWT Token Input
JWT Structure
Decoded JWT
Paste a JWT token to see decoded contents
Header, payload, and signature will be displayed here
When to Use JWT Decoder
Authentication Debugging
Debug login issues, verify user claims, and troubleshoot authentication flows in web applications, mobile apps, and API integrations.
API Development & Testing
Inspect access tokens, validate API authentication, test OAuth flows, and verify token permissions during API development and integration testing.
Token Expiration Analysis
Check token expiration times, validate timestamp claims, and analyze token lifecycle to prevent authentication failures and session timeouts.
Security Auditing
Audit JWT implementations, verify token structure, inspect security algorithms, and validate claims for compliance and security assessments.
Learning & Education
Understand JWT structure, learn about token-based authentication, explore different algorithms, and study real-world token implementations.
Integration Troubleshooting
Diagnose third-party authentication integration issues, verify OAuth provider tokens, and troubleshoot SSO implementations across platforms.
Frequently Asked Questions
What is a JWT Decoder?
A JWT Decoder is a tool that parses and displays the contents of JSON Web Tokens (JWTs). It breaks down the token into its three components (header, payload, signature) and displays the decoded information in a readable format for debugging and analysis.
Is it safe to decode JWT tokens online?
Our JWT decoder processes tokens entirely in your browser without sending data to any servers. However, be cautious with production tokens as JWTs can contain sensitive information. Use this tool for development and debugging purposes only.
What information can I see in a decoded JWT?
You can view the header (algorithm and token type), payload (claims like user ID, expiration time, issuer), and signature verification status. The tool also displays timestamp claims (exp, iat, nbf) in human-readable format.
How do I know if my JWT is valid?
The decoder checks token structure, format, and expiration times. For signature verification, you need the secret key or public key used to sign the token. The tool will show if timestamps are valid and highlight any structural issues.
What JWT algorithms are supported?
The decoder can parse JWTs signed with any algorithm (HS256, RS256, ES256, etc.). However, signature verification requires the appropriate key and is only available for educational purposes in this tool.
Can I use this tool for debugging authentication issues?
Yes, this tool is perfect for debugging authentication systems. You can inspect token claims, check expiration times, verify token structure, and understand why authentication might be failing in your applications.
What should I do if my JWT is expired?
If the 'exp' claim shows the token is expired, you need to request a new token from your authentication server. Some systems provide refresh tokens to obtain new access tokens without re-authentication.
Is this JWT decoder free to use?
Yes, this JWT decoder is completely free with no limitations on usage. All processing happens client-side in your browser, ensuring privacy and security of your tokens.
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