Rockmelt Applies “Design For The Thumb” Philosophy To Port Its iPad Web Browser To iPhone

“Can you do it with one thumb or not?” That’s how Rockmelt co-founder Tim Howes tells me his startup decided what needed to change as it translated its iPad web browser app to the smaller iPhone screen. You’ll still scroll through reams of stories from your favorite sites instead of hunting them down. But you won’t have to reach for the back button thanks to new gestures like swipe-left-to-close.

Funded with $40 million from First Round, Andreessen Horowitz, Accel, and other VC heavyweights, Rockmelt started as a desktop web browsing client focused on social sharing. Rockmelt for iPad launched two months ago to redesign the web browsing experience for touch and eliminate the need to surf. You subscribe to blogs, websites, and social profiles, and Rockmelt delivers all their latest updates into a feed. The whole idea was to make content consumption more relaxing with less typing to fit the iPad’s laid-back form factor.

The app’s gotten modest traction, with it currently sitting at #121 on the iPad news app charts. The team tells me the average users scrolls through about 200 stories a day and shares four times a day — six times more than on the desktop. A few weeks ago it added the option to login via email instead of just through Facebook or Twitter. That increased the number of users who log in and personalize their experience from 50% to 60%, and proved the founders’ hypothesis that the email signup option wouldn’t cannibalize social logins.

Rockmelt IPhone ScreenshotAs popular as the iPad is, Rockmelt wanted to reach a larger audience so it started working on an iPhone version. But the team wasn’t satisfied to just shrink their tablet version. Howes tells me “we introduced new gestures with the idea that you only have one digit to work the whole app.”

For example, you can’t pinch to close a story with one hand. Meanwhile, the iPhone 5’s larger screen made it tough to reach the top left corner where you’d typically put a back button. So Rockmelt for iPhone lets you swipe left to close a story and return to your feed.

Other design tweaks include moving to a single column of stories from the iPad app’s dual columns, and tightening up the story tiles so more can fit on the screen at once. Sharing buttons now pop-up as an overlay instead in their own window that would take up too much room.

If you save stories by swiping right and have Rockmelt for iPad too, your stories are synced between the two apps. Those stories will also sync to your dekstop Rockmelt browser after the next release of that software. Since you’re more likely to be on a cellular connection on the iPhone, Rockmelt tries to respect your data plan by downloading images and media in lower resolution unless you’re on Wi-Fi. Howes says this leads to a 75 percent reduction in data usage.

Abiding “the tyranny of the thumb” like Rockmelt is a good lesson for other developers to learn. If you want people to snack on your app while on the bus, waiting in line, or walking, try to keep it one-handed.

Rockmelt for iPhone is now available in the App Store.