Kayak.com is a travel search engine website based in the United States. Founded in 2004, it aggregates information from hundreds of other travel sites and helps users book flights, hotels, cruises, and rental cars. Kayak combines results from online travel agencies, consolidators such as Orbitz, and other sources such as large hotel chains.

Kayak doesn't sell directly to the consumer; rather, it aggregates results from other sites then redirects the visitor to one of these sites for reservation. Thus, Kayak.com makes money from pay per click advertising, when the consumer clicks-through to one of the compared websites (for example, when the consumer is redirected to the Orbitz website).

This SonicWALL signature identifies legitimate www.kayak.com HTTP traffic.