The API has been rewritten a few times now, it gets over 300 million requests a month. All organic growth, I can’t take any credit for it because I honestly have done nothing to aid it. Only use Google AdWords and it runs on a $40/m VPS.
We introduced paid plans a year ago and had a few sign ups. I think the paid accounts are about $440MRR but I split it with a friend who did all the work around paid accounts. (I didn’t think it would be worthwhile, he did, so he did the work around paid subscriptions)