It’s no secret that your voting history is public information. In fact, when you vote, where you vote, how often you vote, and even your party registration are just a few of the publicly-available data points that political candidates and marketers (including VoterTrove!) can access and use to determine whether you are likely to show up and cast a ballot in any given race.

But, in years past, accessing that information has required contacting the necessary state officials, compiling and formatting the data into a usable format – steps unlikely to be taken by the average citizen. Now, thanks to a new app, it’s easier than ever to know if your friends and family voted, and even figure out who they likely voted for.

It might feel like an invasion of privacy, but it’s all perfectly legal.

From Quartz:

A few weeks ago, I sat down to dinner with my family and opened the VoteWithMe app. Each of my relatives’ names was listed on the screen. Next to each one was a symbol signifying their party registration: Democrat, Republican, or Other. Below that was a long list of elections since 2000 with checkmarks indicating whether they cast a ballot in each one.

VoteWithMe’s magic happens after you give access to your contact list. Based on the names, phone numbers, and addresses in your contacts, the system makes an educated guess of who on the voting rolls you know.

To get people to the polls, a filtering system automatically identifies personal contacts most likely to need a nudge: sporadic voters who might have missed the last election in districts with tight elections (you can choose which political party to screen). Fence-sitters are the ones most likely to be convinced to show up for the polls. A text message integration then helps you auto-fill and send out personalized messages through your phone.

While it might not be much fun to have your vote history available for anyone to see, it’s hard to argue with the effectiveness of social pressure to boost turnout. The app’s inventor claimed that it increased turnout by 2.4% in a recent Pennsylvania special election won by Democrats. In a close race that lift in turnout could be the difference between victory and defeat.

With growing concern among consumers about data privacy it’s hard to say if this technique will ultimately backfire on the campaigns that employ it, but as long as it’s effective in the near term we’re likely to see a lot more of it.