Frequently, location data companies make packages of code that collect phones’ whereabouts. Developers who add this code to their apps can get paid for location-targeted ads, or earn money for providing the location data, or get free mapping or other services for their apps.

The Times asked MightySignal to look for packages of code made by the more than 25 location-collection companies that the firm tracks. The Times excluded code packages that collect location primarily for mapping, as opposed to the sale or use of the data.

The Times restricted results to apps that MightySignal had scanned within the previous six months. Many little-used apps on Android include location-gathering code, so The Times filtered out apps with fewer than 5,000 downloads. Because Apple does not provide download figures for its apps, the iOS apps were not sorted by user base.

Tallying Location Companies

Times reporters examined each company identified in the testing. Those that said they didn’t handle precise location data at all, despite having received it, were not counted as part of the location-tracking industry. In these cases, apps may have sent the data to multiple companies and relied on the recipients to delete it if they didn’t want it.

The Times also did not count companies that were merely processing the data for the app — for security, for example, or to tell the app maker about its own users.

Many location companies receive data from app makers rather than from the apps themselves, a means of sharing that can’t be detected through testing. So reporters also relied on other sources to identify location companies, including outside analysis of the marketplace, privacy disclosures required under a new European law and interviews with dozens of people affiliated with the industry.

Apps Tested

The apps included in the test are listed below, along with comment from the companies. Many other apps share data in similar ways; this list should not be used as a guide to problematic apps. With the exception of one children’s app, each app below collected location data on both Android and iOS when a user gave permission.