On the same day as announcing that Opera has 300 million users, we’re also announcing that for all new products Opera will use WebKit as its rendering engine and V8 as its JavaScript engine. It’s built using the open-source Chromium browser as one of its components. Of course, a browser is much more than just a renderer and a JS engine, so this is primarily an “under the hood” change. Consumers will initially notice better site compatibilty, especially with mobile-facing sites – many of which have only been tested in WebKit browsers. The first product will be for Smartphones, which we’ll demonstrate at Mobile World Congress in Barcelona at the end of the month. Opera Desktop and other products will transition later.

In the short term, this will be good for Opera (less time spent on the rendering engine means more time available to work on user-facing features) and perhaps for some web designers, I can’t help but think it’s an overall step in the wrong direction. We’re left with only three major rendering engines—WebKit, Gecko and Microsoft’s proprietary Trident—which will likely mean a further focus on bad designers building sites for WebKit rather than the standard. Just look back to the bad old days of the Netscape/IE browser war…and the horrible, horrible fallout when Netscape was crushed and only Internet Explorer was widely used for the following decade.On the other hand, having the Opera developers’ expertise contributing to the WebKit project can only be good for the other browsers using it.

300 million users and move to WebKit [Opera Developer News]

Well, there’s another option out now. It’s called Opera Stumbler. It has most of the features of the official StumbleUpon toolbar, but in a menu up on the menu bar instead. It looks like a fairly workable solution, though I haven’t tried it myself yet.

I’m a card-carrying Firefox fanatic, and I couldn’t live without my Firefox extensions, so I doubt I’ll be seeing much use of this for my own purposes, but I know that quite a few of you use Opera (according to Google Analytics). Hopefully you’ll find this useful.