If you have a Linux server or Mac machine you can use the ApacheBench utility to do a quick benchmar for a URL
The utility comes installed by default on most CentOS installations
ab -n 10 -c 5 -d -S -q -I https://abr.business.gov.au/
-n is the number of request
-c is the number of concurrent request
-d -S -q -I are for hiding not required details
You can explore more of the utility by doing
man ab
In my current work it requires to benchmark e-commerce platforms to see how it can handle huge workloads and this tool comes very handy for the Linux geek in me which refuses to use GUI tools. You can also use it to monitor websites with your URL and pipe it through grep & tail to get failed request
ab -n 10 -c 5 -d -S -q -I https://abr.business.gov.au/ | grep 'Failed requests' | tail -c 2 0