Called Open Homes, the platform lets anyone sign up to host a person in need—offering all or part of their residence. A select group of nonprofits and relief worker agencies can then use it to search for temporary housing for those they are helping. The organizations are responsible for identifying and vetting the displaced, searching for and selecting the best housing options depending on preferences and needs, and making the bookings. In other words, it operates much like a regular Airbnb booking—only the price is set at zero, only agencies can do the bookings, and Airbnb does not collect fees.

The company has donated people-hours and expertise in building out the platform itself and has also made cash donations to the International Rescue Committee and to UNHCR, the UN’s refugee agency—but it’s the hosts that will make the biggest social impact.

Currently, there are 6,000 zero-dollar listings on the platform, located all around the world, but primarily in the U.S. and Europe. The site identifies four areas of need: refugees; disaster; medical needs; and homeless. There isn’t a limit on the number of nights a host can house a refugee, but the idea is “nights to weeks.”

The tool has drawn heavy interest from people who are not existing Airbnb hosts but simply want to donate their space for the cause. Of the company’s 6,000 listings currently offered, half are not existing Airbnb hosts. “This is a brand new way for people to contribute and give back in a way that’s actually needed the most,” says Joe Gebbia, Airbnb’s cofounder and chief product officer who has spent much of his time in the past few years leading the initiative.

The company has been using its platform in this way in some form since 2012 when Superstorm Sandy hit New York City. A host in Brooklyn wanted to volunteer her extra bedrooms to those in need, but couldn’t due to the site’s complex payment platform (any booking had to be tied to a payment and linked to a credit card). After she sent an email that quickly circulated around the company (“the thread got real long, real fast,” Gebbia says), the engineering team worked overnight to develop the capability for a “zero-dollar” listing. The company then messaged its New York City hosts that the option was available, and 1,000 people ended up listing their homes for free to those displaced.

From there the company started using the tool during other disasters, from the forest fires in Fort McMurray, Canada to the Orlando nightclub shooting, when Airbnb hosts offered lodging to family members of the victims who had traveled to Orlando. All told, Airbnb says it has used the tool 65 times in 17 countries and provided free housing for 1,900 people. “Anywhere in the world where we have a community, we can help people in need within hours,” Gebbia said. “In some cases, we can help the community respond to people in need faster than the government.”

But much of the work was done manually, with Airbnb making the matches between hosts and victims. And the company felt that rather than just reacting to emergencies, it could do something more proactive. “We started thinking, what are the things we can anticipate and plan for in advance where we can harness that natural generosity on a daily basis?” says Gebbia.

Photograph by Joe Pugliese

In 2015, one of the company’s engineers approached Gebbia with a proposal for how the company could use its software and matching capabilities to help with the global humanitarian crisis. “He shared it with me and it quickly was elevated to the highest levels of awareness in the company,” Gebbia said. “It became a priority.” The company embarked on an intensive research process during which time Gebbia visited Jordan, Macedonia and Greece, as well as major refugee camps in Kenya and Rwanda, and joined President Barack Obama’s Leaders’ Summit on the Global Refugee Crisis during the UN General Assembly last year. “It’s been a crash course in ramping up our knowledge,” Gebbia says.

A team under Airbnb’s global head of social impact, Kim Rubey, was already working on a program to house refugee relief workers in Greece, Macedonia and Serbia, but to address the product challenge, Gebbia formed a new team under his Samara studio that was ultimately spun out and called the Human team. Through test resettlement programs in Oakland and Los Angeles and other efforts to study the refugee journey, they identified the pain points that Airbnb could most help with. The biggest and most obvious: the temporary “soft landing” in a new country, that time after arrival but before permanent housing is being sorted out, when refugees often stay in cheap motels.

The company is just starting the matching process on the new platform, but the end goal is the same one stated by CEO Brian Chesky in January, in the wake of Trump’s travel ban: Airbnb aims to provide housing for 100,000 people in need over five years. “The only way we’ll get there is with scalable technology like this,” Gebbia said after demoing the new platform. “It won’t happen with spreadsheets and phone calls.”

Just like when the company was getting the original Airbnb platform off the ground, there are likely to be rough spots: a refugee that doesn’t assimilate well with his or her host, a bad actor who tries to sneak into the system to get free housing, or any number of routine cultural clashes. As for any rough spots that come up in the process, “we’ll learn as we go,” says Rubey. (One relatively straightforward lesson so far: a lot of refugee families are afraid of dogs.)

One thing that remains to be seen is how local regulators will respond, especially in cities like New York where it’s illegal to rent out one’s full unit in an apartment building on Airbnb for less than 30 days. But, as Gebbia quickly points out, “this is free housing—there’s no money exchanged.” The implication: legally, Airbnb is on the right side of the line.

“I feel like we have a responsibility to do this,” Gebbia said. “This to me is like 21st century corporate philanthropy. We did the check writing. This to me is the next stage. The next level.”