1. Kayak
Kayak is one of the best available in the market in its niche. It is a fare aggregator and a travel metasearch engine that is operated by Booking Holdings. Their products are available in over 18 languages and runs travel search engines checkfelix and swoodoo. They process over 2 billion searches a year for travel information and help millions of travelers be confident about their choices and decisions. With each query, they search hundreds of travel sites to show travellers the information they need to find the right flights, hotels, car rentals and holiday deals. Their growth from since they have started has been exponential and commendable. At present, Kayak is providing tough competition to Google Search Flights and helps travelers find the cheapest flights. They are also working across 7 international brands; KAYAK, SWOODOO, checkfelix, momondo, Cheapflights, Mundi and HotelsCombined.