[keycloak-user] How to verify jwt token with jwt.io or javascript programme

Hello, How can I check the signature of a token (with https://jwt.io/ or an external javascript programm) ? The configuration of my client is of "public" acces type : The keys I use are those defined in the "keys" area of ​​the "realm" created : But that does not work: do you have any idea how could I do this check? Thanks and good day. Regards, Christophe