How we recommend content and list results.
Our recommender systems
We use recommender systems on our sites to help you discover content we think you will like, by weighting factors such as where we believe you are (based on country site, currency selected, IP address or the home airport you have set), what you tell us in the search form (origin, destination, dates, number of guests, etc.), the price of offers and the popularity of destinations or offers, and sometimes our expected revenue. Each factor can be more (or less) important in different cases, depending on what we think is most likely to produce content that is relevant for you.
For example on our landing pages, you will find a number of recommender systems, including:
“Compare vs [our brand]”: Other sites you can use to search for travel, recommended based on travel origin/destination and expected revenue for us.
“Explore the World from”: Destinations you may want to travel to from your current location, based on your home or origin airport, search dates, prices for flights to and popularity of the destinations.
“Hop on, hop off”: Destinations you can fly nonstop to, based on your home or origin airport, non-stop routes available from there in the next month and popularity of these destinations.
“Stays near you”: Cheap accommodations in your area or your destination.
“Explore a variety of stays“: Accommodations in your area or your destination grouped by property types.
“Favorite hotels around the globe”: Hotels you may want to visit, in a rotation pulled from a manually curated list.
“Drive around in”: Cheap rental cars grouped by car categories based on your search destination and dates.
“Your wishlist starts here”: Destinations you may want to save to your wishlist, based on your home or origin airport and the popularity of destinations from there
“Explore” allows you to search for flight destinations by budget and duration, by default based on cheap offers found by other users and ranked by price.
“KAYAK Assistant” allows you to use an AI prompt to ask for flights that match certain criteria, and it will match the free form text you have entered to available filters and apply these filters.
“Recommended Filters” will recommend you personalized filters based on your past user behavior and/or the context of the locations being searched, as well as your search parameters (e.g. dates, number of passengers, cabin class); this could also include popular filters for a given location based on usage on our sites as we believe that users may want to reuse certain filters based on their preferences across multiple searches within a vertical.
Our travel search results are also a recommender system, so please check out the ranking options below for each category:
Flights
Best and Recommended
Just because a deal is cheap doesn’t mean it’s necessarily the best. So by default flights are ranked to give you the best trade-off between price and convenience, based on factors such as duration, price, distance between origin and destination, number of travelers and how you started your search, while applying a result diversity logic to provide you with an array of airlines and time-of-day options. The relative importance of the factors is specific to each set of search results, e.g. price will be less relevant if the cheapest flight is only slightly cheaper, but a lot longer than the quickest flight. We believe that these parameters and their weighting contribute to displaying more relevant search results to the users, since the savings on the cheapest flight option may not justify the hassles such as a long stopover that come with it.
Sometimes, the same flight will be available on several provider sites. We highlight the cheapest provider and the ordering of the other booking options will be based mainly on click-through-rate and cost per click. In case of price parity between several booking options for the same flight, the ordering of booking options will be based mainly on click-through-rate and cost per click. We sometimes also judge the quality of the service you’re getting from a provider site. We’ll highlight things like a provider’s booking or baggage fees, so that when you compare your options, you’re using the total price. And if a provider isn’t upfront with their fees, making their prices less clear, we’ll tend not to recommend them.
We display deals from many different sources, including airlines, aggregators, global distribution systems, travel management companies, online travel agencies; however, our results may not always reflect all available deals.
Cheapest
Looking for the lowest price? We can make that happen. Our price sort gives you quick access to the cheapest and/or the most expensive deals—it’s your trip, so it’s up to you.
Sometimes, the same deal will be available on several provider sites. All of these providers are made visible for you to choose from, but we highlight one main provider based on factors like customer popularity or ratings. Providers can also become highlighted if they pay more for the clicks they get.
Stays (hotels and other accommodations)
Recommended
We use internal algorithms to rank property results as well as sort booking option providers within a given property result. For visual simplicity, we always round up the price to the next whole number.
For property results ranking: by default, results are ranked by our ‘Recommended’ algorithm, which is based on a few key parameters: price, guest ratings and its popularity (measured in clicks). The relative importance of the parameters is specific to each set of search results, e.g. price will be less relevant if the price difference is very small. We also factor in the average revenue potential for us from each hotel result. We believe that these parameters prioritize the most relevant results for the users, while also improving our revenue. We use additional parameters such as the distance from city-center and the number of stars, which we deem less relevant and therefore attribute a lower weighting. You can also sort the results by price, hotel class, review score, and distance (from the destination in your search).
Sometimes, the same deal will be available on several provider sites. We highlight one main provider based on factors such as provider’s price compared to the solo cheapest price and the average revenue potential for us from each hotel result, i.e. an offer may be ranked higher if our expected remuneration is higher, but not if it is substantially more expensive than the other offers. Our algorithms may obfuscate one or several offers if they are not the solo cheapest and they are affecting our or our partner’s monetization. We believe that these parameters balance the relevance of results for the users and improving our revenue. Within a hotel listing, if the solo cheapest offer is not displayed above the “View Deal” or “Select” button, you can see it by looking for the price highlighted in green. The ordering favors private deals if the user is logged in.
Price
Looking for the lowest price? We can make that happen. Our price sort gives you quick access to the cheapest and/or the most expensive deals—it’s your trip, so it’s up to you.
Cars
Recommended
The “recommended” sort for car rental is mainly prioritized by price, revenue potential for us, general click popularity and the popularity of different car classes in each pickup destination (e.g. SUVs are more popular than normal at this pick-up location). For some locales, we also factor in the review score of each rental agency and/or deal providers. The relative importance of the factor is specific to each set of search results.
Sometimes, the same deal will be available on several provider sites. We highlight one main provider based on factors like customer popularity or ratings. Providers can also become highlighted if they pay more for the clicks they get. Our algorithms may obfuscate one or several offers if they are not the cheapest and they are affecting our or our partner’s monetization. We believe that these parameters balance the relevance of results for the users and improving our revenue. Within a car listing, if the cheapest offer is not displayed above the “View Deal” or “Select” button, you can see it by looking for the price highlighted in green.
Packages/Holidays
Recommended
The default “Recommended” sort result for packages is based mainly on the price, the hotel’s guest rating and its popularity (measured in clicks). We also factor in the average revenue potential for us from each package result. We believe that these parameters prioritize the most relevant results for the users, while also improving our revenue.
Within a packages listing, we order our results based on an internal algorithm that balances the prices and our revenue potential for the results shown.
Trains and Buses
Departure time
We have sorted our train and bus results by departure time to make it easier to find an itinerary that matches your schedule.
Cheapest
Looking for the lowest price? We can make that happen. Our price sort gives you quick access to the cheapest and/or the most expensive deals—it’s your trip, so it’s up to you.
Our train and bus prices sometimes include mandatory taxes and fees, depending on locale. Check for additional fees. Some partners may charge for an additional service fee, a fee for additional baggage, or a fee for certain payment methods.