JWT Decoder — Free Online Tool
Paste any JSON Web Token to immediately see its decoded header, payload claims, and expiry time in human-readable format. Ideal for debugging authentication issues, inspecting OAuth tokens, and understanding what claims an API expects. This tool never sends tokens to a server.
100% client-side. No uploads. Your data never leaves your browser.
How to use JWT Decoder
- Paste the full JWT string (including the two dots separating header, payload, and signature).
- The tool immediately decodes and displays the header and payload as formatted JSON.
- Check the 'Expiry' field to see when the token becomes invalid.
- Inspect individual claims like 'sub', 'aud', 'iss', and custom application claims.
Frequently Asked Questions
Does this verify the JWT signature?
No. Signature verification requires the secret key, which you should never paste into an online tool. This tool only decodes the header and payload (which are just Base64url-encoded JSON).
Is it safe to paste a production JWT here?
Because the tool is 100% client-side, the token never leaves your browser. However, as a general security practice, rotate any token you paste into third-party tools.
What JWT types are supported?
Any standard 3-part JWT (header.payload.signature) using standard Base64url encoding. This includes JWTs from OAuth 2.0, OIDC, and most modern auth systems.
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