A new app that is currently a Kickstarter project promises to print all of your smartphone photos for free--with a small catch.

Users who download Flag can get 20 physical photographs printed from their smartphone for free every month in exchange for looking at some advertisements and providing their zip code to marketers, Yahoo Tech reported.

Flagg connects to your smartphone's camera roll and social media news feeds so you can select 20 favorite photos each month to be printed out and mailed to you. App users can edit the photos by cropping and adding borders.

Photos will arrive printed on "museum-quality" laser-cut photo stock with advertisements printed on the back. You get free photos, which you can put in a frame without ever seeing the ad again, Yahoo Tech reported.

Some of the ads will have QR codes, which Flag users can scan and log into with the Passbook app from Apple. Advertisers will use your zip code to offer deals within your area, but Flag promises that no more information will be shared.

"Advertisers will not be able to see users' photos, or know their personal information," Flag founder Sam Agboola said, according to Yahoo Tech. "No names, no addresses. All the targeting will be on aggregated data. You'll be able to advertise to people in a zip code, you won't be able to advertise to John Smith of 123 Main St."

While printed photos aren't a terribly expensive investment, the app makes it convenient to have physical copies of moments that usually stay in your smartphone or worse, disappear when you lose your device.

People who back the Kickstarter project will be able to access a beta version of the app, and their investment will go toward special features they can add to prints. Some extras include larger versions of prints, custom postcards and rounded edges.

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