How an offline app, built by volunteers, became a key tool for first respondents during the earthquake response in Venezuela.

On the second day after the earthquake, Anton went down to what everyone had started calling ground zero , the hardest-hit area. He'd been helping in Caracas before, but now he was heading into a zone with no cell coverage. He didn't have to improvise: he already had the app on his phone.

" CoMaps turned out to be really useful for me because I entered a zone with no coverage and needed it right away," Anton recalls.

A few days later, he joined as a volunteer with a rescue team that had come from El Salvador, firefighters, Civil Protection, several different rescue units, operating remotely, taking instructions from a command center back in their home country. Most of the team didn't know CoMaps. Only one person had access to a map and was guiding the rest.…