|Type||Subsidiary of Priceline.com|
|Headquarters||Norwalk, CT, USA|
|Founder(s)||Steve Hafner, Paul M. English|
|Key people||Steve Hafner
(Co-founder) & (CEO)
Paul M. English (technologist)
(Co-founder) & (CTO)
|Revenue||$224.5 million (2011)|
|Subsidiaries||SideStep, Swoodoo, Checkfelix.com|
|Available in||English (US, UK, India), Danish, Finnish, French, German, Italian, Norwegian, Spanish & Swedish|
|Launched||May 5, 2004
October 2004 (Public Beta) 
February 7, 2005 (2005-02-07) 
Kayak.com is a travel metasearch engine operated by the Kayak Software Corporation (or KAYAK). The company also provides related services and operates KAYAK.co.uk, checkfelix.com, and swoodoo.com. The company was acquired by Priceline.com on November 8, 2012.
In December 2007, KAYAK raised $196 million in a new round of financing from a group of investors, including General Catalyst Partners, Sequoia Capital, Accel Partners, and Oak Investment Partners. Using that funding, KAYAK acquired SideStep, a competing US travel website.
On March 5, 2010, KAYAK sold certain assets related to the website www.travelpost.com and its travel information business to The New Travelco, Inc., a Delaware corporation, which subsequently changed its name to Travelpost, Inc.
In May 2010, the swoodoo brand, a leading travel search platform in Germany, was acquired.
In January 2011, KAYAK closed down SideStep and redirected SideStep traffic to KAYAK.com.
In April 2011, KAYAK acquired all of the outstanding shares of JaBo Vertrieb-und Entwicklung GmbH, or JaBo Software. JaBo Software operates checkfelix.com, a leading travel metasearch website in Austria.
In July 2012 the company announced it would expand into Russia.
On July 20, 2012 Kayak officially went public, trading under the name KYAK. On its first day of trading, Kayak opened up at $26/ - higher than originally expected and closed at $33.18/share.
On September 25, 2013 it was announced that the State of Connecticut would assist KAYAK with a $2.5 million loan to help facilitate their move to the Harbor Point district of Stamford. 
KAYAK was founded in 2004 by Steve Hafner and Paul M. English. Hafner currently serves as KAYAK’s chief executive officer, and English, the chief technology officer. Before KAYAK, Hafner helped found Orbitz in November 1999 and led its business development, advertising sales, marketing, and product marketing activities.
At The Webby Awards, KAYAK received the People’s Voice award in the travel website category in 2008, the Webby Award in the travel website category in 2009, the People’s Voice award in the mobile travel app category in 2011, and three more awards in 2012: both the Webby and People's Choice awards in the travel website category and the People's Voice award in the mobile travel app category.
All-American Muslim advertising
In December 2011 KAYAK announced that it would not renew a contract to advertise on the TLC reality television show All-American Muslim. The decision followed a campaign by the Florida Family Association, a one-man fundamentalist organization "on the Christian right" that says it's "defending American values." KAYAK chief marketing officer Robert Birge wrote that TLC "was not upfront with us about the nature of the show" which "sucked" in an explanation posted to the KAYAK website entitled "We Handled This Poorly."
- "KAYAK.com - Traffic Details". Alexa. Retrieved 2011-07-22.
- "Corporate Backgrounder". KAYAK.com. Retrieved 2009-03-06.
- "Kayak.com: Private Company Overview". Business Week. Retrieved December 26, 2011.
- "KAYAK CrunchBase Profile". CrunchBase. October 23, 2011. Retrieved January 9, 2012.
- "Kayak.com Company Overview". Bloomberg Businessweek. Retrieved January 9, 2012.
- Arrington, Michael (December 20, 2007). "Breaking: Kayak Raises $196 Million, Buys Rival SideStep". TechCrunch. Retrieved January 9, 2012.
- Schaal, Dennis (February 11, 2011). "Kayak has stake in TravelPost rollout". Tnooz. Retrieved January 10, 2012.
- Zinnagl, Lukas (May 6, 2010). "Kayak swoops on German travel search engine Swoodoo [Updated]". Techcrunch. Retrieved January 10, 2012.
- Ostrow, Adam (November 17, 2010). "Travel Search Engine Kayak Files for IPO". Mashable. Retrieved January 10, 2012.
- Womack, Brian (May 27, 2011). "Kayak Software Quarterly Sales Rise on Online Travel Demand". Bloomberg. Retrieved January 10, 2012.
- Duryee, Tricia (March 4, 2011). "Bing Picks Kayak for Travel Search Partnership". All Things D. Retrieved January 10, 2012.
- Taylor, Colleen (May 27, 2011). "Poised for IPO, Kayak Reports Sales Boost and Global Growth". Gigaom. Retrieved January 10, 2012.
- Emerson, Rip. July 20, 2012. "That’ll Fly: Kayak Closes IPO Day With Shares Up Nearly 30% And Market Cap Over $1.2B." http://techcrunch.com/2012/07/20/kayak-ipo-first-day/
- The Next Web, November 8, 2012. "Priceline.com acquiring travel company KAYAK for $1.8B in a deal that includes $500M in cash" http://thenextweb.com/insider/2012/11/08/priceline-com-acquiring-travel-company-kayak-for-1-8b-in-cash-and-stocks/?utm_source=Twitter&awesm=tnw.to_isx7&utm_campaign=social%20media&utm_medium=Spreadus
- Connecticut Department of Economic Development, October 7, 2013. "KAYAK to Expand and Create 50 Jobs in Stamford." http://www.ct.gov/ecd/lib/ecd/press_releases/2013/KAYAK_to_Expand_and_Create_50_Jobs.pdf
- "Steve Hafner General Catalyst Entrepreneur Page". General Catalyst. Retrieved January 13, 2012.
- Welch, Liz (February 1, 2010). "The Way I Work: Paul English of Kayak". Inc. Retrieved January 13, 2012.
- Fisher, Adam (August 24, 2009). "50 Best Websites 2009". Time. Retrieved January 17, 2012.
- "KAYAK Webby Awards 2011". The Webby Awards. Retrieved January 13, 2012.
- "KAYAK Webby Awards 2012". The Webby Awards. Retrieved June 1, 2012.
- The 2010 federal tax forms for the Florida Family Association list Mr. Caton as its only paid employee, earning $55,200. Source:Freedman, Samuel G. (December 16, 2011). "Waging a One-Man War on American Muslims". The New York Times. Retrieved 22 July 2012.
- Freedman, Samuel G. (December 16, 2011). "Waging a One-Man War on American Muslims". The New York Times. Retrieved 22 July 2012.
- Stenovec, Timothy (July 10, 2012). "Florida Family Association Launches Campaign Against Marvel Comics Over Same-Sex Marriage In 'Astonishing X-Men'". Huffington Post. Retrieved 22 July 2012.
- Diaz, Johnny (December 14, 2011). "Kayak won’t renew ads on Muslim TV show". The Boston Globe.
- Elliott, Stuart (December 14, 2011). "Kayak Defends Cutting Ties to ‘All-American Muslim’". Media Decoder.
- Birge, Robert. "We Handled This Poorly". Kayak.com. Archived from the original on December 15, 2011. Retrieved December 15, 2011.
- Official website
- America Online aims to be in vanguard of Internet travel
- Online shopping sites fight customer bailouts, International Herald Tribune
- Struggling upstream, Forbes.com