I went ahead and created a free account in assertible. This is definitely doing what I want (test a simple GET rest api call). I will check further (if it is notifying me when a call fails).
@Others: One minor point to note here is that the free account allows only one hour Scheduled Monitoring, not more frequently.
@Others: One minor point to note here is that the free account allows only one hour Scheduled Monitoring, not more frequently.