Pi-hole is described as 'The Pi-hole® is a DNS sinkhole that protects your devices from unwanted content without installing any client-side software' and is a very popular Ad Blocker in the security & privacy category. There are more than 25 alternatives to Pi-hole for a variety of platforms, including Linux, Windows, Mac, Android and iPhone apps. The best Pi-hole alternative is Portmaster, which is both free and Open Source. Other great apps like Pi-hole are AdGuard, NextDNS, simplewall and RethinkDNS.
Pi-hole alternatives are mainly Ad Blockers, but if you're looking for
Privacy Tools or Firewalls you can filter on that. You can also filter by region, for example
EU-based alternatives if you prefer software developed in the European Union. These are just examples - use the filter bar below to find more specific alternatives to Pi-hole.