Little Snitch, AdGuard, Blokada, AdAway, LuLu by Objective-See, Radio Silence, ufw, simplewall, TripMode, orWall, RethinkDNS, NoRoot Firewall, OpenSnitch, Firewalld, TrackerControl, AFWall+, Mobiwol, BiniSoft Windows Firewall Control, Quantum Flare, Adhell3, DroidWall, Blok: Simple Fast Firewall are some alternatives to NetGuard.