ApiChecker offers Free Trial, but DownNotifier.com does not.
ApiChecker is designed for Medium Business and Small Business.
DownNotifier.com is designed for Large Enterprises, Medium Business and Small Business.
Pricing for ApiChecker Starts at $4.58/Month when Billed Yearly whereas for DownNotifier.com Starts at $14.95/Month.
Some top alternatives to ApiChecker includes Uptime, Uptime Robot, Hyperping, UpTime.onl, updown.io, Uptrends, pingnow.io, 66uptime, Loadping and Pingt.io.
Some top alternatives to DownNotifier.com includes Uptime Robot, DevMonitor.io, UpTime.onl, Odown, Downtime Monkey, SiteUptime, Uptrends, Nodown, pingnow.io and Domain Monitor.