>Product Manager for Cloud Firestore here. It's worth noting we do have the ability to set hard daily caps, as well as budgets that can have alerts tied to them. It's something we also looking at ways to improve it.

Google Cloud user here. A warning: If you ever happen to get, say, frontpage on reddit or techcrunch or other big boost to publicity, your site could be down until the next billing cycle (i.e. 24 hours) and you will have no way to fix it.

This bit me hard one day with appengine and lost us a ton of converting traffic, even though we tried to get the limit increased within ten minutes of the spike (and well before our limit was hit).