What's the carbon footprint for these services? Would be interesting to calculate how much would an average free tier usage pollute. Are there any available numbers from these products?
This seems like it would be hard to pin down, since it would vary widely from project to project. It would kind of be like asking 'what's the carbon footprint of a dev running a test?'. Well, that depends on the complexity of the code they're testing, what computer they're using, what language they're using, the climate of their workspace, and so on.