Opera has confirmed that it is to drop its own proprietary rendering engine, Presto, and switch to WebKit instead, not only for smartphones but also for its desktop browser.

A rumour that Opera was planning a move to Webkit for its Android browser emerged in January, but today's news is of a more sweeping change.

The announcement from Opera states:

To provide a leading browser on Android and iOS, this year Opera will make a gradual transition to the WebKit engine, as well as Chromium, for most of its upcoming versions of browsers for smartphones and computers.

It quotes Chief Technology Officer Håkon Wium Lie who explains the rationale for the move:

"The WebKit engine is already very good, and we aim to take part in making it even better. It supports the standards we care about, and it has the performance we need. It makes more sense to have our experts working with the open source communities to further improve WebKit and Chromium, rather than developing our own rendering engine further. Opera will contribute to the WebKit and Chromium projects, and we have already submitted our first set of patches: to improve multi-column layout."

What does this mean for developers?

It strengthens WebKit, which will be welcomed by many, but not everyone is pleased by the having one fewer web browser to test for.

Co-chairman of the W3C CSS Working Group, Daniel Glazman considers that from the point of view of the CSS Working group one less testing environment means one less opportunity to discover bugs and issues and writes on his blog

"The Web wakes up less fragmented today but this is a sad moment because fragmentation and competition are good for innovation."

While most would agree that competition is good it is fairly obvious that fragmentation is bad. It might be an advantage for a standards organization to have lots of implementations to test its specification against, but having multiple implementations to code for is a tiresome chore.

You could even say that it isn't a huge problem if a small number of implementations get it wrong as long as we know about it and can code to a small set of de facto standards - the smaller the number the better. The issue of competition is also much diluted by the need to conform to a standard - the only place for innovation and competition is in the quality of implementation.

However, there is something unnerving about handing the web over to a single rendering engine. The situation hasn't quite come to this, but now we only have Microsoft's Trident and Mozilla's Gecko to offset Webkit's huge influence. As Glazman says

"One CSS prefix is gone and -webkit-* increases its power."