I think the license here is important as well. I know of a few companies that just paid the $500 - $750 (it's changed over time) to Mike just to avoid even hav

I think the license here is important as well. I know of a few companies that just paid the $500 - $750 (it's changed over time) to Mike just to avoid even having to think about Sidekiq being some sort of GPL license. If it were MIT or BSD like many other Ruby gems, I'd imagine his revenue would have dropped precipitously. Given he called the license out specifically, he likely agrees. It'll be interesting to see what his next project is and if it's a repeatable model. Asynchronous job queueing & processing is something a lot of Rubyists need and many on resque were frustrated. Sidekiq was a very attractive carrot, not the least of which because it was interoperable with resque, leading to a simple migration path. The stick was an unattractive license that was easily removed with a small fee.