JWT Decoder
Debug your authentication flows with ease. Our JWT Decoder allows you to paste any encoded JSON Web Token and instantly view its decoded data. We break down the token into its Header and Payload, allowing you to verify claims, expiration times, and algorithm types.
A critical diagnostic tool for developers working with modern web security.
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How to Decode JWTs
- 1
Paste your encoded JWT string (the three-part dot-separated string).
- 2
The tool will automatically parse the Base64Url encoding.
- 3
Review the decoded Header and Claims Payload in the structured window.
Understanding JWTs
Payload Claims
This section contains the user data and permissions (e.g., `sub`, `exp`, `iat`). Checking the `exp` (expiration) claim is vital for debugging login issues.
Security Note
This tool decodes the token so you can see the data, but it does not verify the signature. You should always use a server-side library to verify token authenticity.
Frequently Asked Questions
Does it require a secret key?
No. Because JWTs are Base64Url encoded, anyone can decode them to see the data. The secret key is only needed to verify if the token was tampered with.
Is my token secure?
Yes. Decoding happens 100% in your browser. We never transmit your token string to our servers.
Why Use This Tool?
- ✓Instant Base64Url decoding
- ✓Clear structural visualization
- ✓Critical for OAuth debugging
- ✓Private and local processing