sfa-checker
There are 2 repositories under sfa-checker topic.
baum1810/minecraft-checker
This Project checks if a minecraft account is a nfa/sfa account or invalid it also says you if the ip you are using is shadow banned from minecraft (shadow bann is if you send too many login attempts to minecraft then minecraft will say that every account is invalid even if it is valid)
baum1810/sfa-checker
a little programm to check if a minecraft account is nfa or sfa