According to UK-based Realmac Software, a new iPhone app - Clear - has already been downloaded over 350,000 times since its Feb. 14 launch. The productivity app centers on To-Do lists and is highly praised for its incredibly practical user interface, based entirely on swipes and pinches instead of on-screen buttons.

“The launch day (Tuesday, Feb. 14) was massive, and by Wednesday…it was number one on App Stores around the world. It’s been an incredible response,” noted product manager Nik Fletcher.

The new app has generated net revenues of about £169,000 so far, after Apple’s 30 percent cut. Clear was a collaborative project, therefore the revenues will be shared between software studio Impending, co-creator Milen Dzhumerov and Realmac.

“Before Christmas we were talking to Milen and Impending about a new project, with four ideas on the table. A couple of them merged into this one really simple To-Do lists app,” Fletcher said. The challenge was to remove the interface clutter rival apps have and to make an app as simple to use as a pen and a sheet of paper.

The result is Clear – an app with such a simple interface that it doesn’t even feature dates or timers. You can just swap your To-Dos for a heatmap that ranks them according to their priority.

The video showing off Clear for the first time has more than 814,000 views so far. Uploaded to Vimeo during the January MacWorld/iWorld conference, the video built great anticipation for the app’s launch on Feb. 14. The app’s running start was also ensured by good press coverage and Apple’s cue to feature it as its App Store App of the Week.

Meanwhile, the developers are working on an update, but Fletcher provided no further details.