JWT Signer & Verifier

Sign and verify JSON Web Tokens (HS256, HS384, HS512) online using Web Crypto API. 100% private client-side JWT tool with zero server requests.

About this tool

JWT Signer & Verifier signs and verifies JSON Web Tokens (HS256, HS384, HS512) locally using the Web Crypto API without exposing keys to external servers.

How to use

  1. Choose Sign mode to create tokens or Verify mode to test signatures.
  2. Select algorithm (HS256, HS384, HS512) and enter your secret key.
  3. Edit claims payload or paste token to verify cryptographic integrity.

FAQ

Are my secrets transmitted over the internet?

No! Cryptographic HMAC operations run exclusively in your browser via window.crypto.subtle.

Does it decode expired tokens?

Yes, it decodes and validates signatures regardless of expiration time.

What does JWT Signer & Verifier do?

JWT Signer & Verifier signs and verifies JSON Web Tokens (HS256, HS384, HS512) locally using the Web Crypto API without exposing keys to external servers.

How do I use JWT Signer & Verifier?

Open the JWT Signer & Verifier tool, then choose Sign mode to create tokens or Verify mode to test signatures.

Related tools