When comparing Uptime Robot vs Nagios, the Slant community recommends Uptime Robot for most people. In the question“What are the best server performance monitoring tools?” Uptime Robot is ranked 5th while Nagios is ranked 6th.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Free
Pro API
With the api ( https://uptimerobot.com/api ) it is possible to automate setup of new monitors, and edit existing monitors, as well as a slew of other functionality, using simple queries and outputs in either XML or JSON (depending on your preference).
Pro Integration with pushover
Get push alerts on your phone when your website goes down
Pro Popular
Being one of the oldest tools of its kind in the market, Nagios is extremely popular. This is usually a good thing because there are a lot of resources on the internet about it such as guides and configuration recipes.
Pro Scalable
Nagios was designed with flexibility and scalability in mind.