WhatsApp has been given the lowest rating for privacy on the annual scorecard from the Electronic Frontier Foundation.
The app is used by more than 600 million people, making it the world's most popular messaging application, and 2015 is the first year it has been included in the EFF's government data protection scorecard.
The watchdog gave WhatsApp just one out of five stars, saying the company did not follow accepted best practice, did not inform users about government demands for their data, and did not make public their policy on keeping data about their users.
"This is WhatsApp’s first year in the report, and although EFF gave the company a full year to prepare for its inclusion … it has adopted none of the best practices we’ve identified," the EFF wrote.
WhatsApp did get credit for their opposition to "back doors" to allow government agencies or other parties access to data, though that policy is one from their parent company, Facebook. The category on content removal requests also did not apply, since the app does not store user content in the same way social networks do.
The only other company included in the report to receive only one star was American communication provider AT&T. Top scorers included Apple, Dropbox, Wordpress, and Yahoo.