Julia Borges was at her cousin’s 12th birthday party when she was shot. The 17-year-old had been standing on a third-floor balcony when a stray bullet hit her in the back, lodging in the muscle between her lungs and aorta.

That was November 8. Luckily, Borges was taken to hospital and has since recovered. Many are not so fortunate. At least 106 people have been killed by stray bullets in Rio this year so far.

Among the most dangerous areas are the narrow streets of the city’s favelas, where more than a million people currently live. Here, the houses are piled up on each other, and the alleys that wind between them are dotted with small squares. These same streets regularly echo with the sounds of gunfire: shooutouts between police and drug traffickers, rival groups of traffickers, or even police-backed militias take place on a daily basis.

Innocent victims are often caught in the crossfire. In many cases residents must lie on the floor or create barricades to hide from stray bullets as they wait for a truce. In 2019, Rio saw an average of 20 shootings a day. Things have cooled slightly since the pandemic began, but there was still an average of 14 shootings every day up until the end of June. Around 1,500 people are shot dead in Rio’s metropolitan area every year.

Living in Rio is like “being a hostage to violence,” says Rafael César, who lives in the neighborhood of Cordovil, west of the city. 

Like many residents, César has started using apps to help keep himself safe. These crowdsourced apps help users keep track of dangerous zones on their way home and let residents warn others about which areas to avoid. 

One of the most