We’re currently experiencing an outage due to errors at our hosting provider. We’re working on the problem and will be back up as soon as possible.
Update: The sites are back up. The problem was a breaking change in how Heroku handles DNS routing. (We hadn’t deployed a new version of our app in three days when the errors started to occur.) We have updated our configuration per a suggestion by Heroku customer support. Thanks to all our customers for their patience while this issue got resolved.