The browser?

I used to have to test every website we developed against all the major browsers and modern versions.

Does that count?
Sure. It's the one I would use as an alternative to Firefox.

Addendum: The problem is that some media sites don't recognize Opera. It once had a settings option that disguised it as Chrome, but not sure if that's still around or is effective anymore.

The "Epic" browser is another one (from India) that sports free anonymous proxy and also heavy-level security features. Of course, like any of the free ones, it is harvesting your browsing data for itself even as it defends you from the trackers and pryings of conventional sources pervading the web.