You won't find "cellphone" listed within Maslow's hierarchy of needs, but the device is certainly making a case for inclusion.

A new San Francisco-focused website, Link-SF, was unveiled Friday with the goal of helping the city's homeless population connect with resources like shelter, food and medical assistance.

The idea for a website alone isn't necessarily groundbreaking, but the intended use case is. Site creators built the service specifically for mobile phones, which have become an important tool in the everyday lives of America's homeless population, too, says Kenshiro Nakagawa, a software engineer at Zendesk who helped develop the site.

Zendesk partnered with Gray Area Foundation for the Arts and St. Anthony's, a San Francisco non-profit offering resources for the homeless, to build and launch the new site. The St. Anthony's Tech Lab, a free tech center in San Francisco's Tenderloin neighborhood for the homeless, discovered that access to web-enabled phones was increasing for those on the streets, prompting the mobile-optimized design for the website.

"Historically, the way service-seekers find out about services is a printed piece of paper, a spreadsheet," says Nakagawa. "That's very different than what the consumer world uses [today]. There's no reason why, besides access to the web, service-seekers wouldn't have the same tools at their disposal."

Link-SF has already been live for a month, but Friday was the official launch with San Francisco Mayor Ed Lee on hand at St. Anthony's to unveil the site. The site currently connects users with local providers for five major services: shelter, food, medical, hygiene, and technology.

Link-SF surfaces nearby service providers based on the user's location, and includes addresses, phone numbers, maps, and hours of operation for each entry. When searching for shelters, users can add filters to narrow the search. For example, a user could specify if they need a place suitable for children or teens, or if they are looking for a women's shelter.

Cellphones are not uncommon among America's homeless. St Anthony's estimates that 45% of people who come through their tech lab have a cellphone, and government programs like Lifeline offer cheap services and phones to low-income consumers.

That doesn't mean Link-SF has plans for a mobile app anytime soon. Most low-income and homeless cell phone users do not have Android or iOS devices where an app would be necessary, says Nakagawa. Instead they often use cheaper phones known as "feature phones," which is what the website was built for.

San Francisco has roughly 6,500 homeless people, according to the San Francisco Examiner. California had the country's largest homeless population in 2013 with close to 137,000 total homeless people, according to the U.S. Department of Housing and Urban Development's Annual Homeless Assessment Report.

Nakagawa says that success with a project like this does not necessarily mean large user numbers, but rather, meaningful user experiences.

"A wild success for us might be 50, 100 or 200 people using the [site]," says Nakagawa. "The goal [is] having the providers and the referral services reach out and teach the service-seekers about this stuff and how to use it on their own terms."