Adblock tests

https://adblock-tester.com (Simple)

https://adblock.turtlecute.org (More thorough)

https://blockads.fivefilters.org (Simple)


Browser/Ad tracking tests

https://coveryourtracks.eff.org


Bufferbloat rating tests

https://www.waveform.com/tools/bufferbloat


Connection benchmark tests

https://speedtest.net

https://www.fast.com


DNS (generic) tests

https://www.dnsleaktest.com

https://www.perfect-privacy.com/en/tests/dns-leaktest

https://one.one.one.one/help


DNSSEC tests

https://dnssec.vs.uni-due.de

https://0skar.cz/dns/en

https://rootcanary.org/test.html

DNS (speed) tests

https://dnsspeedtest.online/


External Port tests

https://canyouseeme.org/


Multitest sites

https://ping.eu

https://www.yougetsignal.com