JWT Decoder and Verifier
Decode JWT claims and optionally verify a supported signature using browser cryptography.
Free browser tool
No Matrix computer needed
✓ No account or card
✓ Use the result right away
✓ Task-specific limits below
Workspace
Use jwt decoder and verifier
Runs in this browser tab
A decoded token is untrusted until its signature is verified. Treat real access tokens as credentials.
Verification happens in this browser. HMAC secrets and SPKI PEM RSA public keys are supported. Never paste a private key.
Token details
Decode the JWT to inspect its header and claims. Nothing is sent to Matrix.
How to use it
Paste a compact JWT to inspect its header and claims, then supply a secret or RSA public key to verify it.
What to check
Decoded claims are untrusted until verification. Supports HS256/384/512 and RS256/384/512, not every JWT algorithm or issuer policy.
Review the result before using it in a published page, application, or agent configuration.
Quick answers
Frequently asked questions
Are decoded JWT claims trusted immediately?
No. Anyone can construct a token-shaped string. Treat claims as unverified until a supported signature is checked against a trusted key.
Which JWT signatures can Matrix verify?
The browser supports HS256, HS384, HS512, RS256, RS384, and RS512. Verification does not replace issuer, audience, or application policy checks.
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