Opera has previewed new versions of its browsers at a press event in Oslo, including a sneak preview of Opera 12, its desktop browser.

Opera Mini 6.5 and Opera Mobile 11.5 will now show you exactly how much data you have used and how much data you will save using Opera Turbo.

That's the company's web compression tech that crushes pages on its own servers - meaning your device doesn't have to download as much data.

Both are available for download from today, initially for Android.

Opera mobile

"A lot of people don't realise how much money they can save on data traffic. People naturally want an easy way to measure how much data they use," said Lars Boilesen, head of Opera Software.

Opera 12

Also shown at the UpNorthWeb event in Oslo was Opera 12, the new version of the company's desktop browser - an alpha is available from Thursday.

Opera's Christen Krogh took TechRadar through some of the features of Opera 12.

"Firstly there's hardware-accelerated graphics featuring WebGL. What we have here is a web app that connects via JavaScript to the device driver and enables you to control the camera. The main change in Opera 12 is the internals, we reimplemented completely our HTML parser and reworked how JavaScript is handled.

Opera 12

"When it gets a web page, it builds up an HTML tree structure. Part of the HTML5 specification is how to specify how browsers behave when they build up this information," Krogh continued.

Opera 12

Saving data

Krogh also demonstrated Opera Mobile 11.5 running on Android 3.x Honeycomb.

"It feels incredibly efficient, with smooth scrolling. You'll never see a checkerboard on this browser again. With Opera Turbo enabled... you see the data savings." We saw 61 per cent saved on a single page, although Opera says compression of up to 90 per cent is possible.

Opera mobile

"In a recent Nielsen study they looked at the time spent on mobile devices in the browser versus time spent in applications. The time spent in the browser is three times longer [than in apps]."

Opera also talked about the data processed by its servers to offload processing from devices running the Opera browser - the company handles more than 12 petabytes of data per month. That's 80 billion web pages.

"If you consider a web page to have 35-40 page elements, then you'll find our servers are executing more than a million HTTP requests per second," continued Krogh. "All those 200 million users standing on each other's shoulders would almost touch the moon."

Other new features in Opera Mini and Opera Mobile include an update to the Opera Presto rendering engine, improved network performance and smaller JavaScript engine memory usage.

Opera Mini and Opera Mobile for Android are available for free in the Android Market.