some feedback.
1. I saw in the change log that you support IPv6, make it more prominent in the front page as well. (maybe add IPv6 support to pingr.io as well)
2. Your pricing is what I was looking for, per request and per location. but the fixed charge thing is what holding me back. maybe a prepaid option would be better. eg: a person adds $10 credit to the account and uses it at pay as you go pricing.