Early on Wednesday morning, as the Eaton fire quickly grew northeast of Los Angeles, Jess Reynolds was glued to Watch Duty, a fire-tracking app on her phone. Reynolds, [a photo editor at Fast Company] who lives in the neighboring city of La Caada Flintridge, hadnt gotten an evacuation warning yet. But as the app gave detailed updates on the spread of the fire, she decided it was time to leave, pulling out of her driveway at 5:30 a.m. Hours later, her whole city was under a mandatory evacuation order.[Screenshot: Watch Duty]Shes one of hundreds of thousands of L.A. area residents who are relying on the nonprofit app for real-time information as multiple fires blaze. Most of the critical information in the app comes from radio dispatches from first responders. Theres nowhere else that information exists in near-real-time besides radio traffic, says Nick Russell, vice president of operations at Watch Duty. Weve assembled a team of retired and active firefighters, dispatchers, first responders, as well as radio enthusiasts who have been doing this for many years. Weve built a platform to get that information in one place, so communities dont have to piecemeal the story together to understand the danger that they are in or not in.[Screenshot: Watch Duty]The app also shares maps of fires, with the option to turn on a wind layer that shows where the fire is likely to move. The map reveals evacuation zones and roads, along with shelter locations. The app shares photo and video updates of fires, air quality data, and other information, with the option to turn notifications on or off for a particular fire.Watch Duty first launched in Northern California in 2021. John Mills, a tech founder, had moved to rural Sonoma County during the pandemic and soon experienced a major local fire. CalFire, the state fire agency, only had time to give updates once a day, and it was difficult for residents to know what was going on. But Mills saw that some volunteers were following radio scanners and sharing updates on social media. He wanted to make that information easier to find.The app began with all-volunteer citizen information officers, but now has a small number of paid staff as well. (It also has a pro version, because the team realized that first responders were also using the app to get the best information.) During a critical event like the current fires in Los Angeles, the team works around the clock to provide important information as soon as its available.Sharing data this way can help make people more likely to evacuate when its necessary, Russell says. When a police officer or firefighter is coming to your door [to tell you to evacuate], they dont have time to sit there and brief you on all the events and why theyre telling you to leave, he says. So what happens is a lot of people stay in their home and they dont leave because they dont understand the danger that theyre in. Watch Duty, by telling that storyline of reports from the start of ignition until the threat passes, is giving people that full story. Watch Duty users often decide to leave before an official evacuation order is issued, avoiding the chaos of traffic in a mass exodus. Others are willing to leave when the order comes, because theyve been following along.[Screenshot: Watch Duty]The information saves lives. In a fire in Malibu in December, one resident told the nonprofit that the app gave her a 15-minute advance warning as the fire was starting to spread. She was able to grab her dog and leavebefore losing everything else. Another family in Reno, Nevada got a notification about a wildfire near their home while they were out a lunch. They left the diner immediately and went home and gathered pets and some important documents, says Russell. As they left, their home burned down.The app also offers an extra layer of protection when government systems dont work. On Tuesday night, as multiple evacuation orders were issued around the Los Angeles area, some residents had issues accessing official websites. What users were experiencing when they went to go look at the countys evacuation map is an error saying that there were too many requests, and to try again later, Russell says.The Watch Duty app is now available in 22 states. As climate change makes wildfires more likelyextreme fire weather that was once seen every hundred years now happens every seven years, and the frequency of extreme fire risk has grown 20 timesthe app is one example in the quickly-growing space of wildfire tech. (The nonprofit also plans to later expand to other disasters, including floods.) The current fires have boosted demand; when I spoke to Russell on Wednesday afternoon, the app had added more than 750,000 users in the last 12 hours.