API-status.com is a dedicated website powered by WatchMouse. It is a free resource that can be used for monitoring and measuring the real time availability and performance of the public APIs of more than 26 heavily trafficked, popular mega web services sites including Google Search, Google Maps, Twitter, Facebook, Digg, Amazon, Foursquare and others.
API-status.com does a call and check for a valid result on each of the APIs and if the result is wrong or is received after four-seconds, it is noted as an error and unavailable. The percentage of availability or uptime is based on the number of errors reported. Additional details on API-status.com include a seven-day history along with a 24-hour glance and performance indication by country.
API-status.com is built using WatchMouse “Public Status Pages” functionality. This feature is included in all WatchMouse paid monitoring plans and allows WatchMouse customers to create their own equivalent of API-status.com for their own websites, APIs, etc. More information is available at http://www.watchmouse.com/en/feature/public-status-page.html.