Adblock tests
https://d3ward.github.io/toolz/adblock
https://adblock-tester.com
https://test.adminforge.de/adblock.html
https://blockads.fivefilters.org
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
External Port tests
https://canyouseeme.org/
Multitest sites
https://ping.eu
https://www.yougetsignal.com