Medical appointment company Zocdoc is offering to handle COVID-19 vaccine scheduling logistics for hospitals and health systems, many of which have spent the early days of the vaccine rollout struggling to handle the crush of demand for doses. Mount Sinai Health System in New York has been using the company’s tool to handle vaccine appointments since mid-December, and has scheduled over 100,000 appointments since.

“It’s for anyone who’s in the front lines of administering COVID-19 vaccinations, to streamline their work. That’s our contribution to the public health effort,” Oliver Kharraz, CEO and founder of Zocdoc, told The Verge. The scheduler is free for any group offering vaccines, even if they aren’t Zocdoc clients.

Without federal coordination, state and local public health departments have been left to coordinate vaccine appointments on their own, often with limited resources. Many makeshift digital platforms across the country crashed or locked people out after thousands scrambled to sign up at once. “It’s one of these things that looks deceptively simple, but it’s deceptively hard to do,” Kharraz says.

The Zocdoc Vaccine Scheduler can slot into an organization’s website to screen patients and book appointments, while shouldering high traffic demands. At its peak, the Zocdoc-run Mount Sinai scheduler was booking 100 appointments per minute, a traffic volume that could overwhelm a system that wasn’t accustomed to that load.

Online tools some health departments and hospitals use to schedule vaccine appointments are also complex, requiring users to navigate multiple input fields or upload attachments. They’ve been difficult for older adults who are eligible for vaccinations to navigate. Zocdoc is used by millions of seniors on Medicare, Kharraz says, so he’s confident the user interface would be accessible to that group.

Zocdoc says it is in discussions with multiple health care organizations and health departments about the scheduler. The team is also working with cities to set up centralized clearinghouses for all their local vaccination sites. In New York City, one challenge has been that there isn’t a single appointment scheduler that integrates every site. People looking for slots have to jump from website to website, and from interface to interface. Kharraz says that Zocdoc could integrate them all together. “It’s just pointless to be going from A to B checking what’s currently available,” he says.

Organizations other than Mount Sinai will start to go live with the tool next week, Kharraz says. “Our goal is to have really national coverage for this,” he says.