Kayak vs Justfly

Kayak searches hundreds of travel sites to find all the possible flights to ensure you don't miss out on the best options. They have the most comprehensive results out of the competition.

One of the biggest advantages of Kayak that most of their competitors don't have is the choice of where to book after you have found what flight or hotel you want. This means you are not locked into a single vendor and can compare the various booking fees etc.

Kayak has a feature called "explore" that lets you answer the question "Where can I go for how much?" Explore is a fantastic tool for initially planning out your trip while finding the cheapest flights.

From CN-Traveler:

You punch in parameters for a trip and how much you're willing to spend to fly there, and your options magically appear on a map. You could punch in, for instance, that you want a maximum-four-hour nonstop flight in January to someplace where there's a beach and the temperature is between 70 and 90 degrees and they speak Spanish, and you don't want to spend more than $500 on airfare; Kayak will spit back your options.

You can plan searches on cruise lines.

Support for both Android and iOS with a simple user interface.

Sign up for email and or mobile phone alerts on price drops for the saved trip.

Find by booking number and last name.

You can search and filter a pickup and drop off time for rental with drivers age range as a filter.

You can filter by one or more stops.

Every search has the option to look for hotels.

You can add two or more destinations at future dates.