stylish

Correction, in my previous reply I meant to say that the Safari version of Stylish (not stylus) has a different developer and doesn’t appear to share the Chrome/Firefox extension’s tracking issues. The code for the safari version is available here: https://github.com/350d/stylish With a quick glance it looks to include google analytics, but that’s only used on the extension’s settings page and doesn’t send browser history or anything like that. JS isn’t my forte, though, so if anybody else could take a look and confirm that’d be great.

I was curious about this too. The source is on GitHub (https://github.com/350d/stylish), but who knows if Apple checks that they're the same when they're approving it. Edit: I should note that it collects analytics, but it can be turned off in the preferences. I don't remember if it's on by default, but I suspect it is.

Safari has been my main work browser for a while, and I really like it, but as soon as you need an extension, it's a sad story... It's not that you cannot make good extensions for Safari. Apple closed the doors for non registered (and paying) developers, even for homebrewing extensions for your own use. For instance, there's no good userscripts extension for Safari as of now, and the userstyles extension is adware (randomly opens MacKeeper affiliate tabs: https://github.com/350d/stylish/blob/bc8f01693000cf00421c7b9...). The only major complaint I have with Firefox (as of 57) is with openh264. It grabs a whole CPU core for a video that Safari handles at a fourth of that or less.