Facebook managed to put its vast treasure trove of user data to good use after Friday’s tragic terror attacks in Paris: the social network customized its safety check feature to let users know whether their friends and loved ones in Paris are safe. Users can check for the safety of their contacts here.
The safety check was used by 4.1 million people to mark themselves as safe within the first 24 hours after the attacks, according to a Facebook spokesperson. 360 million people were notified that their friends were safe.
Users in the area are being alerted by Facebook’s mobile apps, asking them whether they are safe, and offering to check on any of their friends. The app has also been sending out alerts to anyone who has friends in Paris, and Facebook’s website lets anyone check on the status and whereabouts of their friends as well.
Most people have likely seen Facebook’s safety check for the first time today, but the company actually launched it in response to the Nepal earthquake earlier this year. At the time, Facebook CEO Mark Zuckerberg wrote: “When disasters happen, people need to know their loved ones are safe. It’s moments like this that being able to connect really matters.”
Facebook wasn’t the only tech company to directly reach out to its users in Paris after the terror attacks. AirBnB sent its customers in Paris an email advising them to stay in place and follow the directions from local authorities, and Uber used its app to advise users to “not move unless absolutely necessary.”
Paris-based Twitter users took initiative into their own hands and quickly established a hash tag — #PorteOuverte, which translates to “open door — to open up their homes as temporary shelters to others caught up in the chaos.
Updated 11/14: This post has been updated with data from Facebook about the use of the safety check feature.