Skyscanner is the official app from the service by the same name. Its aim is to help you find the cheapest flights to any destination, just like the website. All you have to do is choose the city of origin and destination, as well as the approximate date you want to travel. After a few seconds, you'll see all the results from different companies that offer flights to your desired destination, sorted by price. Although the results are sorted by price by default, you can also set different filters. For example, you can choose the exact time you want to fly or specify the number of layovers. The app searches for flights from more than a hundred different companies like Iberia, Ryanair, Air Europa, etc. Although the app is completely free, it has no affiliation with any of these companies, so it always shows the cheapest deal without favoring any one airline over another. Skyscanner is a very useful tool if you fly often. With it, you can plan your trip from your Android in minutes, and even save a lot of money if you're lucky.
Requires Android 2.3 or higher