We recognise the importance of providing users of our platform with easy access to information regarding the EU Digital Services Act (DSA) and our obligations pursuant to it. This page covers the areas of Advertising, Transparency Reporting, Recommendation Systems, and Content Guidelines related to our obligations under the DSA.
To comply with our DSA obligations, we will inform users when an advertisement appears on our site by clearly and prominently labelling it with a Sponsored or Promoted badge. We will also identify on whose behalf the advert has been placed, who paid for it, and the main parameters used to determine recipients. For additional information about our advertising, you can review our advertising policy.
KAYAK has prepared a transparency report to comply with its DSA obligations. This report provides insights into the content moderation activities that we engaged in during the reporting period, including the volume and nature of content removed from our platform. The report can be downloaded here.
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.
“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 personalised filters based on your past user behaviour 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:
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 travellers 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 order 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 order 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.
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.
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 prioritise the most relevant results for the users, while also improving our revenue. We use additional parameters such as the distance from city-centre 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 monetisation. 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 favous private deals if the user is logged in.
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.
The “recommended” sort for car rental is mainly prioritised by price, revenue potential for us, general click popularity and the popularity of different car classes in each pick-up 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 monetisation. 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.
The default “Recommended” sort result for holidays 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 holiday result. We believe that these parameters prioritise the most relevant results for the users, while also improving our revenue. Within a flight+hotel listing, we order our results based on an internal algorithm that balances the prices and our revenue potential for the results shown.
We have sorted our train and bus results by departure time to make it easier to find an itinerary that matches your schedule.
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.
We search hundreds of travel, airline, hotel and rental car sites at once to bring you options from across the web. While we always strive to have the most accurate and current information, there are occasional inaccuracies. Sometimes, it’s because the provider site isn’t updating their inventory with us or hasn’t connected to our site properly, or maybe another traveller has already booked that deal. This last scenario will sometimes happen because we cache results in order to keep site speed up (so you’re not waiting around). For example, if you and another traveller start the same search within the same minute then we’ll most likely show you both the same results. At the very least, provider sites should give us an updated inventory of prices every 24 hours. While we do search as many sites as we can, we’re still not able to search them all. There are also cases where we don’t display results from certain providers for technical or commercial reasons, or simply because we can see them having a negative effect on customer satisfaction.
Reviews appear on our site in a few ways. We show reviews and review scores from other well-known travel websites.
On our site, we collect and display reviews in a few different ways.
For Flights and Cars, we display reviews collected directly from our customers who have a confirmed booking, whereas for Stays, we display reviews from both our customers and from partner websites. For reviews collected directly from our customers, only users who have an account with us and agree to receive emails from us are contacted and asked to provide a review. Customers may also leave reviews directly on our Trips platform.
The customer will only be contacted after the reservation has concluded, which ensures that our reviews contain first-hand knowledge and reflect customers’ personal experiences. For Flights and Cars, the user selects a rating from “poor” to “excellent.” We then convert this into a numerical rating on a scale of 1 to 10 and attach it to a qualitative review (if provided) to facilitate easy comparison and evaluation. Our method eliminates fake reviews or social media endorsements, and instead relies on verified customers to provide genuine reviews. For reviews on Stays, our scores are calculated by averaging the scores of reviews that we collect and reviews collected by our partners.
All reviews are published after doing automated profanity checks. Whether positive or negative, we won’t display or will remove reviews that violate our guidelines or terms of review providers, similar to our Terms of Use, including reviews that include or refer to (among other things):
And to make sure reviews are still relevant, we may stop showing reviews once they are three years old – or if there has been a change of ownership or another major change such as a renovation.
We may also ask users to submit travel tips. These tips are evaluated through automated means and will not be published if they are not deemed sufficiently useful.
We will also remove illegal content and reviews that do not comply with the above after manual review by our content moderation team based on a notice sent to us through the feedback form.
KAYAK prioritises requests from Trusted Flaggers in accordance with the EU Digital Services Act. As a Trusted Flagger you play an important role in identifying illegal content on our platform and we value your expertise in detecting and identifying content that is non-permissible on our platform. If you are appointed by a Digital Services Coordinator and would like to notify us about illegal content, please fill in the feedback form.
If our decision to remove content can be appealed pursuant to article 20 of Regulation (EU) 2022/2065, we will provide a statement of reasons for our decision and information on how to lodge a complaint against the decision. Any complaints will be reviewed manually by our content moderation team against our content guidelines and the outcome of the review will be notified to the complainant.
If a recipient of the service is frequently found to provide manifestly illegal content or someone is frequently submitting notices or complaints that are manifestly unfounded as envisaged in article 23 DSA, then we will review the matter in accordance with article 23(3) DSA and, if the repeat offence is confirmed, we will issue a warning to the person in question, respectively suspend them after a prior warning. At this time we do not envisage such cases happening and will give examples of the facts and circumstances that we take into account when assessing whether certain behaviour constitutes misuse and the duration of the suspension if and once we see such cases.
We respect intellectual property rights and expect our users and partners to do the same. Our policy is to:
Privacy and other confidential data
In line with our Privacy Policy, we take our privacy and data protection obligations seriously.
We don’t allow content that may put the privacy of our guests and other data subjects at increased risk. For example, users or partners erroneously share personal data about other persons, including but not limited to sensitive or special category personal data, credit card numbers, national identification numbers, drivers, other licence numbers, addresses, or any other information that isn’t publicly accessible. This policy may also apply to the hotel staff’s names.
We don’t tolerate content intended to scam, defraud, or deceive others for monetary gain. We remove phishing links, malware, known or suspected scam content, and fraudulent content and permanently restrict the accounts of known fraudsters or scammers.
We have appointed Momondo A/A, Farvergade 10, DK-1463 Copenhagen K, Denmark, CVR DK 20181397 as our Legal Representative. You can contact the representative at feedback@momondo.com
In accordance with our obligations under the EU’s Digital Services Act, we estimate that the average monthly recipients* of our service (including KAYAK, momondo, HotelsCombined, SWOODOO, checkfelix, Cheapflights, roomsearch) in the European Union from 1 August 2024 up to and including 16 February 2025 is well below 45 million.
This is only an estimate based on the data available to KAYAK at this time and the limited guidance in the DSA. This estimate is required to be published under the DSA and should not be used for any other purpose. The methodologies used to estimate average monthly recipients as defined in the DSA require significant judgment and design inputs, are subject to data and other limitations, and are inherently subject to statistical variances and uncertainties. This estimate may be revised upwards or downwards as KAYAK refines its approach and in response to the publication of methodology by the European Commission.
Please refer to the Booking Holdings Inc. Investor Relations website for metrics we consider relevant to KAYAK’s business.
* ‘recipient of service’ is defined under the DSA as “any natural or legal person who uses an intermediary service, in particular to seek information and make it accessible”. This requires counting users to whom information was displayed by our service, even if that user did not make a transaction.