[Foulest]

The same thing happens with Google's SafeBrowsing, Microsoft's SmartScreen, Bitdefender TrafficLight, or Emsisoft Browser Protection. Osprey essentially combines multiple already existing browser protection extensions into one.

[lostmsu]

SafeBrowsing uses local database AFAIK.

[Foulest]

Ah! True. I guess they realized it would be better to do that than have the extra network strain.