This may seem silly, but I was wondering if there are any tools or applications that can be used to test or verify connection speed from an ISP. On our network we have a 10G connection from our ISP, but I have no way of proving that we are getting the agreed upon speed.
If you want to check the actual circuit capacity then use iperf3. You need your ISP to run it on a server at their end, and you need to run it on a server at your end. Both ends should ideally plug directly into the fibre.