After that article ran, I started getting tips that the use of location data from cellphones was more widespread than I had initially reported. On the site, people were anonymously discussing their work for companies that used people’s precise location data. I called sources who knew about mapping and location data. For apps to send GPS data to companies, the information has to be transmitted from the phone to a computer server far away. Aaron used a technical tool that could read and record all that data as it was sent from the phone.

Source: New York Times December 14, 2018 14:06 UTC