[Question] synthetic indices used to rate all charities: What kind of star ratings exist?

I want to learn more about char­ity rat­ings. Do you know watch­dogs or­ga­ni­za­tions (be­sides Char­i­tyNav­i­ga­tor) that use star rat­ings? E.g. I heard about an or­ga­ni­za­tion called “Give Star”, but I could not find a web­page. Do you know more?

Many thanks in ad­vance!