[camillomiller]

3 reasons, not ordered by importance:

1. This is gonna be unpopular, but: the target OS X users for this low/medium priced softwares are more willing to pay instead of pirating, than their counterparts on Windows.

I say that based on empirical assumptions, I have to say, but what I notice is a general cultural difference on this point.

2. A huge part of the web creatives community uses Macs, therefore it makes sense for these devs to focus on OS X

3. I don't know about Sketch, but for Tumult the reason can be found in their official "about" paragraph:

"Tumult Inc. was founded in 2010 by ex-Apple employees whose mission is to make the next generation of tools to produce beautiful web sites and apps. Tumult Inc. is funded by Y Combinator"

[kyriakos]

I guess #3 is the most important factor here but from my personal experience #2 is not really true. Maybe it is for US based web developers but its not a worldwide phenomenon. There is a large percentage using OS X but it's small compared to the combined Windows/Linux user base. I'm sitting in an office with 6 webdevs right now and only 1 of us uses OS X. It not because OS X lacks something but its mostly because Apple product availability, pricing and familiarity is not the same everywhere.

About #1, totally agree there is more piracy on Windows than OS X but I am not sure it makes a difference in the number of sales. i.e. a lot of people will pirate it but isn't that the ones that would have not paid for it in the first place?

[PauloManrique]

There are several countries, like Brazil for example, that a Mac can cost more than a house. So I guess we don't have a "culture" of buying software because we can't afford a overpriced system.