Is the username - password receipe possible? With an imposed username (that is chosen for the user depending on its first/last name)

hey @nano_ck this is possible. First, checkout our username password flow (https://supertokens.com/docs/emailpassword/common-customizations/username-password/overview). Then you can override the

signUpPOST

api on the backend to additional check that the username is based on the name from the formFields, and if not, return a general error which is displayed on the frontend.

By overriding the backend you mean editing the node module?

no. See this: https://supertokens.com/docs/emailpassword/advanced-customizations/apis-override/about

Ok thanks