'Anonymous' Whisper app tracks its users and shares data with authorities

The company behind Whisper, a social media app that promises users anonymity and claims to be the "the safest place on the internet", is tracking the location of its users, including some who have specifically asked not to be followed.

Whisper is also sharing information with the US Department of Defence gleaned from smartphones it knows are used from military bases, and is developing a version of its app to conform with Chinese censorship laws.

The US version of the app, which enables people to publish short messages superimposed over photographs or other images, has attracted millions of users, and is popular among military personnel using the service to make confessions they would be unlikely to publish on Facebook or Twitter. Some post from secret bases such as Guantanamo Bay or Diego Garcia.

Asked to comment last week, Whisper said it "does not follow or track users". The company added that the suggestion it was monitoring people without their consent, in an apparent breach of its own terms of service, was false.

But on Monday - four days after learning that The Guardian intended to publish this story - Whisper rewrote its terms of service. It now explicitly permits the company to establish the broad location of people who have disabled the app's geolocation feature.

Whisper has developed an in-house mapping tool that allows its staff to filter and search GPS data, pinpointing messages to within 500 metres of where they were sent. The technology, for example, enables the company to monitor all the geolocated messages sent from the Pentagon and National Security Agency. It also allows Whisper to track an individual user's movements over time.