JWT validator · Guide
Validating HS256 JWTs
HS256 is the most common JWT algorithm. Understanding how it signs explains why validation needs the same secret that created the token.
Symmetric signing
HS256 uses HMAC with SHA-256 and a single shared secret. The same secret both signs and verifies, which is simple but means every party that can verify can also mint tokens.
Validating in the browser
Supply the token and the shared secret; the validator computes the HMAC and checks it. Keeping this client-side ensures the secret is never transmitted.
Frequently asked questions
Can I use this for production work?
Yes, for inspection, formatting and quick generation. Still review the output before committing it to production code or configuration.
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