When Neta Schreiber's friend was assaulted by men at a party ten years ago, the perpetrators fled when Schreiber and others burst into the room.
It was that strength-in-numbers moment that gave Schreiber the idea to develop SafeUp, a phone app that is designed to help specifically with women's safety.
It was launched in Tel Aviv in March with the help of the municipality.
And, according to Schreiber, it already has 20,000 users. She explains how it works.
"SafeUp is community based network of women that enable them to help each in real time to prevent sexual harassment and to feel safer in their day-to-day life. Whenever one of our 20,000 users feel unsafe she just opens the app, clicks on a button and she hops onto a call or video call with her nearest guardian, trained women that are available and prepared to help her."
The app allows women to signal their location and summon help from other subscribers. Schreiber hopes SafeUp could be used in bigger cities, like London.
The recent abduction and murder there of Sarah Everard while walking home from a friend’s house has stirred up public demand for better measures to protect women.
In distress, a user can share her live location with a list of women she provided in advance.
Or be connected to a conversation with volunteer women "guardians" to receive reassurance and guidance.
Should the user or the "guardians" deem the situation an imminent danger they can also call police through the app.
SafeUp then taps into the phone's camera and microphone to record evidence.
For less extreme circumstances, it can geolocate "guardians" within 500 metres of the user, summoning them instead.
Schreiber says this is so much more than an app.
"We actually built not just an app, a movement. A movement of women that help each other and make the streets safer for women. And we hope that in five years from now, we will be the biggest movement of women that make the streets safer."