Every API should have an uptime monitor to track the status of the API. The bounded context of the API being monitored, which operations you monitor, how often you monitor the uptime of an API will depend on the type of API, as well as enterprise and industry policies. Uptime monitoring should be automated and provide results and monitoring dashboard for both API producers and consumers.
Monitoring APIs should be standardized across APIs with guidance for how and what gets monitored as well as what platform services and tooling are available for doing the monitoring–ideally it is just done for teams as part of overall platform services. Uptime monitoring results and history should be available for all stakeholders to search and review, and stored as part of API contracts when it makes sense.
It can help to publish the latest monitoring results as well as historical summaries directly in API contracts or the repositories used to manage API contracts. This allows the overall state of an API contract to be defined based upon the real-time availability and historical reliability of an API. This contract-based approach uses uptime to establish trust in the contract between producer and consumers.