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

SuperTokens.com

is there any `onUserCreated` function?
basically like a hook, when a user created, do something

I know it's possible to do in `consumeCode`, `thirdPartySignInUp`. Just wondering if there's a cleaner way to do this

Hey! The intended way is to override the signInUp api function and do your post use creation logic there

See the post login operations section on the docs

unknown

this one right. awesome. SuperTokens is pretty well built

https://supertokens.com/docs/thirdpartypasswordless/common-customizations/handling-signinup-success

You most likely want to use the backend method.  But depends on what you want to do post login