Onavo Extend (for iPhone)

Because no one can see "data," few people grasp how much of it they burn through every month. Especially on smartphones, all this data can result in additional mobile phone plan charges you'd probably prefer not to pay. iPhone owners (running iOS 4.3 and later), and especially those on a limited data plan, should download the app Onavo Extend (free) immediately... over Wi-Fi, of course. Android users, don't despair: there's an , too.

Onavo Extend is a compression app that works quietly in the background to minimize how much data your phone uses when it's not connected to Wi-Fi. It takes all your data-intensive activities, such as getting mapped directions, sending and receiving email, and browsing the Web, and trims the fat. It's this core money-saving feature that makes Onavo Extend an Editors' Choice iPhone app, although its decent customization options and handful of reports don't hurt either.

How Onavo Extend Works
Onavo Works by routing all Internet-related actions through its servers, where data is compressed before being sent to your device. This is similar to what RIM does with its BlackBerry devices, using server-side compression to reduce the total amount of data transmitted. The Opera Mini Web browser also uses server-side data compression, although it only tackles activity happening within its own app. Onavo works across apps, including Safari, Mail, and so forth.

Since all your data is being routed through Onavo's servers, privacy, security, and scalability should be of concern. So here's what we know: Onavo's system runs on Amazon's EC2 cloud servers. Its servers are protected by multiple layers of security, and nothing is actually stored on them except for aggregated and anonymized metadata, such as what types of apps are being using. That information is used to help illustrate your data usage and savings, as well as for research to help improve the service.

Onavo cannot read or compress encrypted SSL traffic, however. The only exception is Microsoft Exchange mail traffic, which requires the user's explicit approval. This can be turned off from the app's Settings.

Interface and Performance
Setting up Onavo Extend takes little more than downloading it from the App Store. The app then installs a configuration profile on your device, which redirects your Web connection through Onavo's proxy.

Once installed, you may want to configure a few of the settings, like how much quality you'll let Onavo sacrifice when it compresses images, for instances. You might also choose to not compress email. Other than those optional customizations, Onavo is ready to roll immediately.

Whenever your iPhone operates via a 3G or LTE connection, Onavo Extend will do its thing. You don't have to babysit it or repeatedly launch it. Onavo pauses automatically when a Wi-Fi connection is being used and resumes when it's lost.

Onavo just works. And on the chance that it doesn't (some users have reported interference with MMS and voicemail, which we were not able to reproduce), there's a button called Diagnose and Repair that attempts to resolve any problems by reinstalling the app.

The user interface consists of just three menus: Data Saver, Reports, and Settings. Data Saver tells you if the app is running and how much data you're currently saving, as a percentage, for different types of uses, like Web and Exchange Mail. The Reports area presents a graph and associated list that breaks down your data usage statistics per month, or from the month's start to date. The Settings menu provides those few options mentioned earlier, such as image compression.

Onavo worked flawlessly throughout our tests. We tried the app on iPhone 4 and iPhone 5. If you leave the image-compression quality at the default setting, "medium," you'll likely notice the difference in sharpness on websites that typically have great graphics, like CNN.com and NYTimes.com. Slide the image compression up until it registers as "high," however, and your eye won't be able to see the difference.

Regular text on websites is unaffected by the compression, so you never have to worry about a page becoming unreadable. Even when you zoom in, text is every bit as clear as it is with data compression turned off. It should be noted that routing your data through Onavo's servers has an effect on speed, but it isn't drastic. Web pages take longer to load, but only by a few seconds.''

If you choose to use email compression, another of the options, Onavo reformats your emails to plain text, meaning no more bold, italics, and other formatting, and no more images either. At the end of these emails you'll see a message that says, "This message has been downloaded as plain text." If you want to see the full, uncompressed email, you can scroll down a bit further and tap on the Download Full Message button.

iPhone Data Extended
In our testing, Onavo reported savings of upward of 50 percent on data usage (with image quality set to Medium) for Web content and Exchange mail. We also saw a 43 percent reduction in Twitter use, as well as 33 percent reduction in data for iTunes/AppStore. Note, though, that Onavo Extend can't compress VoIP data, like Skype calls, or streaming video, so save those Netflix and YouTube videos for when a solid Wi-Fi connection is at hand. But 50 percent is still an impressive figure. If you regularly use 1GB of data per month, it means you would save 500MB.

For international travelers, where every megabyte counts, Onavo Extend is an essential iPhone app. And if you're looking to downgrade your monthly data plan to save money on your monthly bill, it's a great tool to help you monitor your data consumption habits, and in many instances, help you lower them.

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