SuperTokens is an open source authentication solution offering features like: Different types of login: Email / password, Passwordless (OTP or Magic link based).

SuperTokens.com

Once client Application send token (generated by SuperToken) to backend API, how backend API will validate the token

https://supertokens.com/docs/session/common-customizations/sessions/session-verification-in-api/overview

the `rid` is to tell the backend sdk which recipe to route the request to. It has nothing to do with token verification.

ok , if we have single recipe then no need to mention ?