JWT Decoder & Validator - Decode JSON Web Tokens Online
Decode and inspect JWT tokens with expiry check
About this tool
A free online JWT (JSON Web Token) decoder that lets you paste any JWT and instantly see the decoded header, payload, and signature. JWT tokens are used extensively in modern web applications for authentication and authorization, but they are encoded in Base64—you can't read them directly. Understanding what's inside a JWT is crucial for debugging authentication issues, verifying claims, and understanding token expiry.
Our JWT decoder instantly decodes any token and displays three sections: the Header (algorithm and token type information), the Payload (user claims and metadata), and the Signature (cryptographic hash). The tool automatically detects if the token is expired and shows a clear indicator: green for valid tokens, red for expired tokens.
Unlike many JWT decoders online, this tool runs 100% in your browser—your tokens are never sent to any server, making it completely safe for decoding sensitive authentication tokens. You can use this tool for debugging, learning about JWT structure, verifying token contents before making API calls, or understanding authentication claims in your application.
How to use this tool
Paste your JWT token
Copy a JWT token from your browser console, authorization header, or local storage and paste it into the input field.
Click Decode
The tool instantly parses the token and displays the three sections: Header, Payload, and Signature. Check the expiry status indicator.
Review the claims
Examine the payload to see user information, roles, permissions, expiry time, and any custom claims stored in the token.
Copy sections as needed
Use the Copy button on any section to copy the JSON to your clipboard for documentation, debugging, or analysis.
Frequently Asked Questions
What is a JWT and why is it encoded?
A JWT (JSON Web Token) is a standard format for securely transmitting information between systems. It's Base64-encoded (not encrypted) to create a compact, URL-safe string. The three parts (header, payload, signature) are separated by dots. Encoding compresses and standardizes the format, not to hide data.
Is it safe to decode tokens online?
For public tokens and testing, yes. This decoder runs entirely in your browser—tokens are never sent to our servers. However, for highly sensitive production tokens, consider decoding locally or using secure offline tools. Remember: decoding doesn't validate the signature.
What does the expiry status mean?
The "exp" (expiration time) claim in the payload indicates when the token becomes invalid. Green "Valid" means the token hasn't expired yet. Red "Expired" means the token can no longer be used for authentication. This is just informational—verify tokens server-side.
Can I edit a JWT and use it again?
No. Even if you modify the payload, the signature will no longer match, and the server will reject it. JWTs are tamper-proof—the signature ensures integrity. Creating valid signed tokens requires the private key, which you shouldn't share.
What's the difference between decoding and validating?
Decoding reads the contents (what this tool does). Validating checks if the signature is correct using the secret key (requires server-side verification). This decoder only reads the contents. Always validate tokens server-side for authentication.