Exactly the reason why I decided not to pay for Firebase and instead went with gradually rolling my own solutions. Their Realtime Database is extremely conveni

Exactly the reason why I decided not to pay for Firebase and instead went with gradually rolling my own solutions. Their Realtime Database is extremely convenient and pretty useful for web apps, but there's no way to limit the connections and track bandwidth usage in real time. It's basically an open door for anyone with only your Security Rules to block data access. There's no logs to even see if your rules are working as expected, nor where your connections are coming from. They didn't even have that simple blue line showing basic usage in OP's post until recently. The profiling tool mentioned in the OP is also recent and doesn't give a proper picture. It's just really pathetic. They sell themselves as a service company for startups, but one of the biggest things startups need to do is manage their costs, which Firebase doesn't provide in any form. And now since Google bought them, their support will be near non-existent as with all Google products. Having said all that, their Free tier is great for live prototypes and doesn't require adding payment information. Just make sure you're not tying yourself in if you want to progress. Make thin wrappers around their libraries and export your data regularly if it's not throwaway.