Thanks! Right now it's Windows only because it hooks deep into the system to handle the formatting and transformation properly, which is totally different on Mac.

However, a macOS version is the #1 request I get. It is definitely on the roadmap! If you want, you can drop your email in the form at the very bottom of the site (under "Don't Miss What's Next") and I'll notify you specifically when the MacOS version is ready.

I've been working on something super similar. https://github.com/paulirish/markpaste

There's now a CLI that'll read and update your (Mac) clipboard with the result. For this italic use case you'll have to edit the source but it won't be that bad.