When Lovely, a free apartment search platform based in San Francisco, wanted to test its service in beta in 2011, it found two willing local partners (Twitter and Square) happy to provide some testers.

Both companies were hiring and their new employees had to find apartments.

And, as anyone living here knows, finding an affordable apartment in this city can be, well, a nightmare.

By November 2011, Lovely was open to the public in the city; a year later it had scaled nationally, and had launched an iOS app.

“Our mobile engagement is huge,” says founder Blake Pierson. “Our mobile traffic has already passed that on the web.”

Lovely has a nice UI. Clusters of color-coded listings appear on a map as you zoom in and out to view the details. The newest listings are orange, which is the company’s main brand color. You can filter the listings by all the usual metrics–price, number of rooms, neighborhood, pets, etc.–and instruct the app to send you alerts as well.

“We talked to lots of people and tried to codify existing consumer behavior into the product,” says Pierson. The alert system is like a personal assistant in your pocket–if you set up an alert it will send you a push notification whenever something you're seeking comes on the market. The web and mobile apps sync up. You can opt-in to sharing your location and the app will display rentals right around where you are at that moment.”

Given how competitive apartment hunting often proves to be, one of Lovely’s features is particularly useful – a pre-configured message you can send to the landlord asking when you can see the apartment.

Another tool, the Renter’s Card, is a digital profile that lets a landlord see your employment information, credit score, and other data such as links to your LinkedIn profile – all of which may help your search succeed.

Through a sharing function, roommates can sync up accounts and alert each other whenever a new listing looks promising.

Pierson says Lovely is also building up profiles not just of renters but of landlords as well. “We're excited to be building a platform around trust and transparency,” he told me.

Although the company does not disclose specific numbers, it says it has hundreds of thousands of active users nationally, and that there have been over 100,000 downloads of its mobile app. It also is sending some 20,000 push notifications per day at present.

The venture is angel-backed with a staff of 12 located in SoMa. It found its office space in a live-work building through Lovely, of course.