The app, created by Ari Sprung and Kobi Snir, sounds a warning when a red alert siren goes off to warn of a missile attack about 15 seconds in advance.
The Yo app was initially created as a joke, but Sprung and Snir put it to good use after they teamed up with developers to send a "Yo" to Israelis and supporters abroad when a rocket is about to hit. People who sign up to follow the handle "RedAlertIsreal" receive the warnings.
"People who have relatives and friends in the affected areas who want real-time updates on what is happening have been downloading the app, as have many people around the world. Our servers have been overloaded with download requests over the past several days," Sprung told The Times of Israel.
The surge of attacks between Israel and Hamas has caused the app to overload, leaving the developers to try to find the best method to service its users and gain exposure.
"We don't charge for the app, and it's supported strictly by donations, which somewhat limits us," said Sprung. "We need more server space so we can get this app into the hands of more people. More people than ever want to know what is going on in Israel in real time, and our app, unfortunately, is necessary in order to spread that information."