Skyscanner - Skyscanner.com compares over 1000 airlines to find you the cheapest airfares, fast.
Tripadvisor - The Tripadvisor mobile app is available for the Android and iOS platforms. It can be used to create reviews of hotels, restaurants, and to chat with other travelers on Tripadvisor forums.
JetRadar - Compare flights from hundreds of airlines & travel agencies
NetBuddy - Netbuddy is a virtual network operator for a mobile device.
Kiwi.com - Find and book the best low-cost flights all around the world
Wikivoyage - the free worldwide travel guide that anyone can edit.