Norwegian browser developer Opera has announced that it is going to end the use of its own rendering engine, Presto. Over the course of 2013 the company will switch its browser products to use WebKit, the rendering engine used in Apple's Safari and Google's Chrome. Specifically, Opera says that it will base future software on Chromium, Google's open source project that contains most, but not all, of the code used in Chrome.

Opera will show a preview of its first Chromium-based smartphone browser at Mobile World Congress in Barcelona later this month.

The browser company, which boasts of having 300 million users, says that it has already made its first contribution to WebKit: a set of patches to make WebKit's handling of CSS columns as capable as Presto's.

Opera's announcement didn't provide any explicit reason for switching. Opera CTO Håkon Wium Lie said that WebKit had good support for standards and good performance, but the same is true of Presto. Opera has stuck it out with its own engine for this long; why switch now?

While unstated, the reason is likely to be the growing WebKit monoculture, especially on the mobile platforms where Opera is most widely used. Android and iOS both use WebKit-powered browsers. Content on the mobile Web is widely designed for WebKit alone, and many sites depend explicitly on WebKit-proprietary features. This is often the case even when standard, browser-independent equivalent features are available. The result of this is that Opera users can be left behind, faced with sites that don't display correctly—even though, with a modicum of care and attention on the part of Web developers, the content should work fine.

Opera could have gone the route that Microsoft has chosen, trying to educate Web developers and providing tools to make cross-platform testing and development easier, but perhaps the company was familiar with Norwegian king Cnut the Great's demand to the tide that it cease rising, and felt that asking Web developers to stick to standards was similarly futile. Historically, the company has tried to do just this, but its success at influencing real Web developers has been limited; for all the emphasis placed on standards, many developers don't, in practice, care about them.

Mozilla developer Robert O'Callahan expressed disappointment with Opera's decision, saying that it was a "sad day for the Web" and suggesting that Opera might find its ability to influence Web standards reduced. He also said that it makes Mozilla's job harder, as that group too is endeavoring to promote Web standards over "coding to Webkit."

The decision also called to mind the blog post made a year ago by Daniel Glazman, co-chair of the World Wide Web Consortium's CSS Working Group, imploring developers to use standards and not make WebKit and its features a monopoly.