App developer Dan Nolan said Google has been sending him the names, suburbs and email addresses of consumers using his app featured on Google Play -- enough to "track down and harass users who left negative reviews," he told ZDNet.
Nolan said he discovered the customer data on his Google "merchant account" recently, even though Google is not asking explicit permission from app buyers to share such information with developers.
"This is a massive oversight by Google," Nolan posted on his blog. "Under no circumstances should I be able to get the information of the people who are buying my apps unless they opt into it and it's made crystal clear to them that I'm getting this information."
Nolan said the same practice for paid apps was applied globally.
"If you bought the app on Google Play (even if you canceled the order), I have your email address, your suburb and in many instances your full name," he said.
"This is a massive, massive privacy issue Google. Fix it. Immediately," he wrote in his blog.
Google had not responded to a request for comment, ZDNet said.