JWT online tools

https://jwt.io - Basic JWT decoder, helps you quickly inspect the JWT structure.

https://www.scottbrady.io/tools/jwt - JWT generator, this tool helps you create test JWTs using asymmetric keys and also create the JWK asymmetric keys.

https://jwkset.com/generate - JWK generator, it allows you to generate new JWK/PEM key sets for RSA, ECDSA, Ed25519, and X25519, and even create JWKs from existing PEM keys.