Why should you care? Let's crunch the numbers. Hopper has amassed 17 million installs in just a couple years, and secured $83 million in funding along the way. To deliver the best deals, its algorithm consults around 10 to 15 billion historical flight prices per day. And, over time, it learns from your preferences to dish up personalized recommendations. The startup told TechCrunch its predictions are 95 percent accurate, up to six months in advance.

With its latest feature, Hopper is hoping to do the same with hotels. Its tech will collect 10 million price quotes daily for over 500 hotels in New York City, which happens to be its most popular travel destination -- making it the ideal place to start. Of course, there are plenty of rival booking services out there already, so it will have its work cut out.

Like flights, hotels will be displayed on a color-coded calendar (and through a new map interface). Once you modify your selection -- using filters for rating and location -- the app will tell you whether to buy, wait, or if prices are expected to go up. Hotel profiles are also on hand in the form of Snapchat-style Stories. The update is initially available on iOS, and more locations (including San Francisco, LA, Miami, and more) will arrive soon.