Test sites

PC Magazine Speed Test
BB Reports Speed Test
Vidnoz speaker output and balance test
Vidnoz webcam and microphone test
Henrik Gemal's BrowserSpy - see all public info on your computer
GRC - test a large selection of potential computer vulnerabilities (go to "Services" and select "ShieldsUp!" and on that page press "Proceed"), There you will find tabs to test File Sharing, Common Ports, All Service Ports, and view Browser Headers.

AMTSO phishing test site. Check your anti-virus to see if it detects an attempted phishing exploit.

These test sites will reveal if your computer is open to intrusion from malicious intent:

https://dnschecker.org/port-scanner.php . To use these three categories from the drop-down menu - Check Custom Ports, Server Ports and Application Ports. All should show "Timed-Out". If not, changesettings on your router or firewall.