Messaging apps more and more are trying to swipe Snapchat's mojo, rolling out an assortment of updates that reflect the wildly popular app's panoply of polychromatic filters and face-altering effects, among other features. Facebook, which leads the copycatters, last week added a camera-zooming function to its mobile app that's been available on Snapchat for some time. Also last week, Facebook-owned Instagram unveiled live stories, mimicking another Snapchat staple. Meanwhile, Google is gearing up this fall to launch the app Allo, which will share obvious similarities with Snapchat. "The Snapchat killers are all nipping at its heels in their own way," said marketing consultant David Deal. "[They] are challenging Snapchat's dominance of content scarcity and creative storytelling." Here, a breakdown of how Facebook, Google and other challengers stack up.