Earlier quoted context omitted.
Does that mean if my webapps get DOSed or something like that, and I can‘t react very quickly, I could face a bill potentially in the thousands of dollars? Currently considering switching from Heroku, but fixed pricing is a must. I‘d rather they shut down my apps temporality in case something is out of control, then get broke ;-) Any other recommendations besides fly.io?
No, we don't bill people for traffic from attacks. We also waive fees from big, legitimate bursts. The intent of our bandwidth pricing is to allow high usage, sustained bandwidth workloads. It's not to sneak one over on you.
You have enumerated a lot of alternatives so far (prepaying, waiving attack costs) but you still haven't addressed the number one scenario that everybody has been asking about, and which was the reason why Heroku was such a hit: do you offer a flat fee which, if exceeded, simply shuts down the app until the next billing cycle?