Arguably the two most popular photo apps, Hipstamatic and Instagram announced a partnership allowing users of the former to share their photos on the latter. It marks the first time the 17-month-old Instagram—with its user base of 27 million—has opened up its API to third-party imports, as the likes of Facebook and Twitter are still closed off from pushing photos into Instagram (outward from Instagram is allowed).

In Instagram, Hipstamatic photos will now feature a clickable “Taken with Hipstamatic” attribution prompting users to buy the app, suggesting a profit-sharing agreement between the two. Instagram may also benefit from the fact that the arrangement moves them from the realm of app to social network—one comprised of active content creators instead of passive commentators, an attractive quality in the world of advertising.

[via Fast Company