That's right. I've had a tiny vm running for years and have never paid anything.

But they hold your credit card and you gave them permission to bill you if you get more traffic

There are ways to automatically kill billing (and thus service) on a project in response to cost overruns.

Please share the ways, thanks.

I was thinking of this example: https://cloud.google.com/billing/docs/how-to/notify#cap_disa...

But that documentation admits it simultaneously kills everything immediately (not great) yet you may get billed more anyway (even worse).

It's notable that Azure can do better here because they have to (the expensive Visual Studio product comes with "free" Azure credits, you aren't paying for them so there is nobody to "bill" if you run out, they just shut stuff off). They appear to do "better" by just eating the extra cost after shutting off. That's still a better user experience though.

This is a real problem. You set up a cloud service on Friday. You believe it should cost about $10 per day. On Monday you discover it already cost $500 so you switch it off immediately. Oops. Still, only $500 not a big problem right?

And then on Tuesday the billing software explains that ah, there's $1800 extra for that service, we calculate it eventually but we don't promise it'll happen immediately. Now you're $2300 down. And this can continue for several days at big cloud providers because "eventually" is apparently good enough.

The best way is to specify limit on the credit card.