JWT Validator
FreeValidate and verify JSON Web Token signatures
About JWT Validator
When authentication fails, a JSON Web Token is often the culprit, but its compact, base64 form hides exactly the details you need: the claims, the algorithm, and whether the signature actually checks out. The JWT Validator from ToolHub by Codaiman decodes a token into its header and payload and verifies the signature so you can see what is really inside.
Paste a token to read its claims, inspect the signing algorithm, and check expiry, and supply the secret or public key to confirm the signature is valid and untampered. It is built for debugging auth flows, inspecting tokens from an API, and confirming a token was issued and signed as expected. The tool runs in your browser with no account, returning results instantly so your tokens and keys never leave your device.
Common uses
- Decoding a token during an auth bug to inspect its claims and expiry
- Verifying a JWT's signature with a secret or public key to confirm it is untampered
- Checking which algorithm a token uses when debugging a signature mismatch
- Inspecting issuer, audience, and subject claims while integrating with an identity provider
- Confirming a token has not expired when troubleshooting a 401 response
How to use
- 1
Configure options
Set your preferences using the options panel below.
- 2
Click Generate
Click the process button to generate your result instantly.
- 3
Copy or download
Copy the result to clipboard or download it directly to your device.
Why ToolHub?
- Instant error detection
- Detailed error messages
- Standards compliant
FAQ
Can it verify the signature, not just decode?
Yes. Provide the secret for HMAC tokens or the public key for asymmetric ones, and the tool verifies the signature is valid.
Are my tokens and keys sent to a server?
No. Decoding and verification run in your browser, so tokens and signing keys stay on your machine.
Which algorithms are supported?
Common JWT algorithms including HMAC (HS256 and similar) and RSA or ECDSA based signatures are supported for verification.
Does it check whether the token is expired?
Yes, the decoded payload exposes expiry and issued-at claims so you can confirm the token's validity window.
Can I use JWT Validator on mobile?
Yes — ToolHub is fully responsive and works on iPhone, Android, tablets and all modern browsers. No app install needed.