The product I currently work on depends on 3 different vendor APIs and, as you would expect, their non-Prod environments go down fairly regularly.

I found it very frustrating that I never knew when their services came back online. So I decided to build a healthcheck endpoint which integrated with Jenkins and Slack and notified me, via Slackbot, once their services came back up. This meant I could switch back and start testing tickets again asap. When you have tight deadlines, and service regularly go down, every minute counts!