In the latest privacy dustup surrounding a supposedly anonymous service, the Whisper app is said to be tracking users’ locations. Reuters

No one is anonymous in the 21st century -- no matter how much tech companies try to convince us otherwise. That’s one of the disturbing takeaways from a Guardian expose Thursday in which reporters Paul Lewis and Dominic Rushe claim the social media app Whisper has been tracking the location of users who specifically opted out of being tracked.

The two-year-old app, a product of WhisperText LLC in Santa Monica, claims to be a place where people can post secrets and other sensitive information without fear of being discovered. But it turns out the app has been monitoring information about its users’ whereabouts, according to the Guardian. What’s more, Whisper has been sharing information with the U.S. Department of Defense.

The company is reportedly able to locate users through their mobile IP addresses. That would be a violation of Whisper’s own terms of service -- or at least it was. The terms were apparently rewritten just days before the company learned that the Guardian had planned to publish an expose. The new terms now grant Whisper the right to establish a user’s general location, the Guardian reported.

Whisper is increasingly used by journalists, including reporters at IBT Media, seeking newsworthy information from anonymous sources.

Whisper was quick to deny the Guardian story, with a lengthy statement claiming that the company does not collect or store personally identifiable information. “To be clear, Whisper does not collect nor store: name, physical address, phone number, email address, or any other form of [personally identifiable information],” the company said. “The privacy of our users is not violated in any of the circumstances suggested in the Guardian story.”

Neetzan Zimmerman, Whisper’s editor in chief, blasted the story on Twitter in a series of more than a dozen tweets. He also fielded questions from journalists and other Twitter users.

The potential bombshell is the latest privacy-related controversy surrounding a supposedly anonymous service. Over the weekend, some 90,000 photos and videos were reportedly hacked from Snapchat, the messaging app that says it deletes transmitted information after a set amount of time. In that case, Snapchat denied it was hacked and blamed a third-party app that saved Snapchat images.

Regardless of who’s to blame -- or how extensive the breaches may be -- the dustups over Snapchat and Whisper may cause problems for companies that are staking their future on the promise that users can expect online anonymity.

As Facebook Inc. continues with its plans to develop an anonymous app and a possible foray into healthcare-based communities, stories like the one published by the Guardian on Thursday will likely give users serious pause. And they should. The idea of true digital anonymity is one fraught not only with ones and zeros, but large gaping breaches.

Got a news tip? Email Christopher Zara here. Follow him on Twitter @christopherzara.