Started in 2014, Trying to list all server monitoring and APM Solutions

Back in September 2014, I wrote about an article that touched on the subject of server performance monitoring. After which, a reader asked me via LinkedIn: “I am using New Relic to monitor my cloud servers but need an alternative. Any suggestions?” So I wanted to share and expand on my answer to that question by creating a quick/go-to list of all the server monitoring and APM solutions out there, as well as get some feedback on tools being used. I haven’t tested all of these services listed. But have used more than one third of them. Some, such as SolarWinds, Nagios and New Relic I have been using for over a decade. Any feedback on whats missing and/or what should be removed from this 5 year old list is very welcomed. Full list comment below...