Software as a Service (SaaS) is a cloud computing model that provides software applications over the internet, without requiring the users to install or maintain them on their own devices. SaaS vendors are responsible for hosting, managing, and updating the software applications, and providing technical support and security to the users. The key performance indicator (KPI) that would best measure the risk of a service outage when using a SaaS vendor is the frequency and duration of unplanned downtime, which is the amount and length of time that the software applications are unavailable or inaccessible due to unexpected events, such as network failures, server crashes, power outages, cyberattacks, etc. The frequency and duration of unplanned downtime indicate the reliability and availability of the SaaS vendor, and the potential impact of the service outage on the users’ business operations and productivity. References = 3