So far here is what I've been able to find.

https://antifawatch.us http://antifawatch.org

They are both watchdog type websites. The first one is based on individuals the second one is based more on events, though the second one desperately needs to be updated.

Edit1: here is a good website detailing some of the violent history of antifa

https://www.discoverthenetworks.org/organizations/antifa/

So far here is what I've been able to find.

https://antifawatch.us http://antifawatch.org

They are both watchdog type websites. The first one is based on individuals the second one is based more on events, though the second one desperately needs to be updated.