The service for checking literacy is capable of identifying mistakes in your text, even if you have carefully proofread it. Such is the reality, as the human factor plays its role! However, Orfogrammka is a paid service, and sometimes there is a desire to look for free alternatives. Unfortunately, it turns out that there are simply no similar services, and other systems do not detect many errors that Orfogrammka easily finds. Therefore, for texts that I treat with particular attention and responsibility, I always run them through this service for assurance.