JWT Encoder

About JWT Encoder

A JWT encoder builds and signs a JSON Web Token from your payload and secret. Enter your claims and a secret, pick HS256, HS384, or HS512, and it generates a signed token with HMAC. Signing runs entirely in your browser, so your secret is never transmitted — ideal for creating test tokens for API development.

Frequently asked questions

Which algorithm should I choose — HS256, HS384, or HS512?

HS256 is the common default and interoperates everywhere. HS384 and HS512 use larger HMAC digests if your system requires a stronger margin. All three are symmetric (HMAC), signed with the same secret used to verify.

Is my signing secret safe?

Yes. The token is signed in your browser — your secret and payload are never sent to a server. Still, avoid pasting a production secret you don't want on a client at all; use throwaway secrets for testing.

Can I decode the token I create?

Yes — paste it into the JWT Decoder to inspect its header and payload and confirm the claims came through as expected.

Does this support RS256 or other RSA/ECDSA algorithms?

No. This encoder signs with symmetric HMAC (HS256, HS384, HS512) only. RS256 and ES256 use asymmetric key pairs and aren't supported here.