It’s not mentioned in the article (understandably), but writing an extension for desktop Safari is very similar to writing an extension for Chrome. One can even

It’s not mentioned in the article (understandably), but writing an extension for desktop Safari is very similar to writing an extension for Chrome. One can even use the same codebase in most cases — the biggest differences are that Safari is a little more conservative in what it gives extensions access to and any Chrome-specific JS obviously won't work.