https://en.wikipedia.org/wiki/Public_recursive_name_server
8.8.8.8, 8.8.4.4, 2001:4860:4860::8888, 2001:4860:4860::8844: Private and unfiltered. Most popular option.1.1.1.1, 1.0.0.1, 2606:4700:4700::1111, 2606:4700:4700::1001: Private and unfiltered.1.1.1.2, 1.0.0.2, 2606:4700:4700::1112, 2606:4700:4700::1002: Private, block malware.1.1.1.3, 1.0.0.3, 2606:4700:4700::1113, 2606:4700:4700::1003: Private, block malware and adult content.9.9.9.9: Private and security aware. New player that blocks access to malicious domains.208.67.222.222: Old player that blocks malicious domains and offers the option to block adult content.199.85.126.20: Old player that blocks malicious domains and is integrated with their Antivirus.185.228.168.168: Private and security aware. New player that blocks access to adult content.77.88.8.7: Old player that blocks malicious domains. Very popular in Russia.8.26.56.26: Old player that blocks malicious domains.Additional reading: https://freedom-to-tinker.com/2018/04/02/a-privacy-preserving-approach-to-dns/