Which platform should you build for first?

Once upon a time, software-creators had only a few platforms to build on. Today, there are many to choose from.

Chrome: The world's most popular desktop browser will take you far.
Slack: The fastest growing enterprise app to date.
Facebook: Reach 900 million people with Messenger.
Windows: Has ~85% of the PC market share.
Mac: Among other things... Menu bars apps are great.
Linux: Why not.
Web: By far the most popular platform makers are building on today.

“Write today, for future.”