hem is a synthetic monitoring tool which monitors HTTP resources on a regular schedule, storing details of the time taken and the reponse code returned. I’ve been using Uptime at work for a while for endpoint monitoring and over the time we’ve been using it made a few tweaks or plugins for it - in particular being able to send metrics from Uptime to Graphite. There were also some more substantial changes we were considering making and we’d built up a number of supporting scripts to populate the checks via the Uptime API when hosts changed.