How Do You Monitor Your Apis at Night?

I’m a backend developer and lately I’ve been struggling with API downtime going unnoticed until morning. Existing tools feel too heavy or expensive for small projects.

So I started building a lightweight API monitoring tool to send alerts when something breaks — especially useful at night.

I’d love to hear: how do you handle monitoring your APIs? Do you rely on tools like Pingdom, Datadog, or roll your own scripts? What works and what doesn’t?