I think that bandwidth consumed by Circle should be free, since we're also hosted in AWS. Maybe somebody who knows more about the details of Amazon's billing can confirm/deny.

bandwidth is free in the same region, but not across regions.

*edit and I believe not if you end up using the public IP address instead of the internal ip address.

if you use the ec2 public dns it will resolve to an internal ip when the request comes from within ec2

A very good question. I'll see about crunching some of the logs to break it down by subnet.

Great. Whoever the major commercial users are have a financial incentive to keep the service performant. They should all at least be sponsors at some level if they're not already.

Here is a partial log, every /24 that had more than 10k hits in the last 24 hours: https://gist.github.com/evanphx/9361755

Top 5 are hosting providers. Makes sense.

isn't bluebox where travis is hosted?

Hey, as I mentioned in another part of this thread, my startup crunches those logs for a living (and they're sadly not really designed for crunching by anything that comes off the shelf). Ping me if you'd like a hand doing the crunching.