Side note: I just wanted to comment on the variance of HN submission popularity. OP submitted this same amazing tool as a "Show HN" 20 days ago, with very similar title and shorter description [0]. It got no votes.
Today this submission is climbing rapidly. Was the tool very different 20 days ago? I honestly don't know! But you never know how submissions will perform here. It feels pretty random, which makes sense, and also is part of the fun of HN.
Microsoft bought Hotmail back in 1997. Hotmail was powered by Unix servers until 2004, despite MS's best efforts to transition to their own Wintel-powered backend [0]. These things take time.