Searching OTAs and aggregators

The 10 Best (and Worst) Airfare Search Sites for 2021

Frommer’s regularly pits the best airfare search engines, aggregators, and booking engines against each other in a battle royale to see which can find the lowest price on 25 different searches.

This year saw quite a shakeup. Some of the biggest names (HotwireFlightNetworkGoogle FlightsFareness, and CheapTickets) are out of the top 10 entirely, an old favorite (Hipmunk) went out of business, and a scrappy new contender has seized the crown. Here are your new winners (and losers).
The Best Airfare Search Engines: A Word on Our Methodology
A Word on Methodology
We started with 20 top-rated sites, but four of them delivered results that were duplicated on a corporate sister site. Since they’re clearly using the same internal search engine, there’s no sense in listing that engine twice, but we do let you know within the ranking if a sister site delivered a clone of the same results.
We tested the remaining 16 sites on both last-minute flights (leaving the following weekend) and APEX fares (booked six weeks out). We covered major gateways (NYC to LAX, Miami to Rio) and secondary ones (Philly to Rome). We threw in a curve ball (Denver to New Delhi) and included a flight with no North American legs (London to Barcelona) to see how well each handled Europe‘s Wild West of low-cost carriers. We also ignored any itinerary that would be hell to fly—basically anything increasing total travel time by more than half through excessively long layovers, too many stops, or flying way out of your way just to change planes. Airlines may think that makes for a viable plan, but we don’t.

Finally, we used a complicated, weighted scoring system for each search that rewarded two points to any site that found the best fares, one point for second-best, nothing for average results, a negative point for high prices, and minus two for the sites that returned the worst fares. Fares within 1% of one another were considered equal.

An aggregator is only as good as the OTAs it canvasses
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What our terms mean
There are a few things to keep in mind before you search.

• An aggregator is only as good as the OTAs it canvasses. There are booking engines that find prices themselves (Expedia, Priceline, Hotwire). And then there are aggregators—sites that do not book tickets but instead search dozens of booking engines, airfare sites, and OTAs (online travel agencies) and compile the results in one place; you then click through to the one of your choice to make the actual purchase.

Some of the booking sites these aggregators show you are better than others. As with any unfamiliar company, always do a quick check and a complaints search for red flags. Also, some OTAs are prone to dangling lead prices a few bucks below what they will actually offer once you click through to the site, and some misleadingly categorize “direct” flights—which do actually stop, but do not require you to change plane—as “non-stop.” Even the best OTA may sometimes accidentally direct you to a site that posted inaccurate prices, and these OTAs may come and go before aggregators realize they should be eliminated from the roster.

• You must search on your own. Southwest annoyingly does not allow its results to be aggregated or sold through third party OTAs. However, given Southwest’s competitive fares and free luggage, it's well worth the additional step of searching it directly.
Best and Worst Airfare Booking sites: 10: Pricline
#10: Priceline

Trading William Shatner for Kaley Cuoco hasn’t helped Priceline improve its results, landing it dead last yet again. Only twice did Priceline find the lowest fare in our tests— but that low fare was also matched by many sites that outranked it. Most of its results muddled around in the middle or back of the pack at best, and it found the worst fares three times. Priceline’s saving grace has always been “Express Deals,” an opaque fare in which you only get to pick your airports and travel dates, but not flight times, airlines, or stopovers—just a guarantee there will be “0–1” plane changes. However, in this year's study, none of its Express Deals were actually the lowest-priced (in the case of NYC–LAX, the Express Deal was actually among the worst).
Pros: Opaque fares claim they can save up to 40%, but they don't always do so
Cons: Performs middling to poorly on price; limited filters; doesn’t include low-cost carriers
10: Expedia
#9: Expedia

How the mighty have fallen. Now that it owns Travelocity and Orbitz, Expedia runs all of the former Big Three booking engines, so you now get the exact same results on all three. It’s a shame those results are so lousy. Several years ago, Expedia was safely in the middle of the pack. Now it has slipped to the bottom for its utterly middle-to-end-of-the-road search results. It never, not once, found the best price, and only three times out of 25 did it find a next-to-best price (twice, it was for the NYC-LAX flights). On the other hand, it was in last or next-to-last place in seven searches. It actually excelled or failed on the same searches as the last time we ran our tests two years ago, which suggests it hasn’t done much to change its methods or algorithms, allowing other companies to outpace it. Yes, there are six other sites that fared even more poorly and didn’t even make this list, but still: Expedia may have a famous brand name, but we see little reason to bother using it.

Pros: Shows baggage fees; fare alerts; flexible date prices
Cons: Pricing is only fair to poor outside of major routes; limited filters
9: CheapOAir
#8: CheapOAir

The results from this smaller discount OTA were all over the place. It performed the strongest of any on our list for several last-minute international fares, so it can be handy for that. But CheapOAir’s results on flights booked ahead of time ranged from above average to sub-par—finding the best NYC–LAX fare, but the worst NYC–Paris once. Like Expedia, it inexplicably wanted to charge nearly double the going rate for a direct flight from Philadelphia to Rome. 

Pros: Vacation packages; showing details on fare rules (and, for some US carriers, seat selection map); alternate date fares
Cons: With a few exceptions on last-minute international travel, not very good at finding the best price
Note: The aggregator originally won our 8th place slot, but it closed up shop in January 2020, clearing the way for CheapOAir to rise one rank.

Yes, that, the one famous for hotels. It has added airfare searches and it has done surprisingly well. Oddly enough, although the results have recently been powered by its corporate sister sites, Kayak and/or Priceline, the search results differ often enough—as many as half of the results are different—that each deserved its own entry into our contest. That said, failed our tricky Philly-to-Rome search by coming up with a price nearly double what the best were offering. However, alongside Kayak and Agoda (higher up our ranking) it did find the best price on our quirky Denver-to–New Delhi route.
Pros: Shows luggage fees and restrictions, but only after you click through to each result’s details; very simple interface; plenty of filters for results
Cons: Is mostly fair-to-middling on price
6: Kayak
#6: Kayak

Kayak is probably the most famous aggregator but frankly, its results were mostly middle-of-the-road. On the positive side, it has one of the most complete sets of filters, including obscure ones like landing times, layover cities, alliances, in-flight amenities, and aircraft type. Beyond that, it falters. It did well on pricing a last-minute jaunt from New York to Paris, but was the only site out of 16 that failed to find a direct Philly to Rome flight on American. In fact, since 2017 Kayak has slipped two places in the ranking on price alone—and has also become less user friendly. Kayak has inexplicably removed a handy feature that it was one of the first to offer years ago: a “Flex Search” option that checked fares up to three days on either side of your dates (also a monthly price calendar). Why would it remove that excellent feature? Kayak also used to include Amtrak, but, alas, no longer.

Pros: Fare alerts; vacation packages; excellent filters; advice on whether to buy now or wait based on historical price trends
Cons: Other sites usually match or beat it on price; it removed several of the great features that once set it apart
5: Agoda
#5: Agoda

For an outfit that started as a specialist in Asian hotels, Agoda has expanded impressively. Agoda now aggregates airfares as well, and impressively so, faring better than its corporate siblings, Kayak and The results pop up lightning fast, and it has among the most complete set of filters. It also never fell into our “worst price” category, though it was among the second-worst a few times. On the other hand, it only found the best price one time, but did come up with a second-best price about a half-dozen times. In other words, there’s a good reason it sits at #5—solidly middle-of-the-road, runner-up results, but with a great interface. Given how new Agoda is to this game, we expect great things as it improves its algorithms.

Update, Summer 2021: However—and this is a big caveat—since we conducted our most recent pricing investigation, Agoda has earned the ire of customers who have reported it to the Better Business Bureau; you can read through the compaints on the website

Pros: Quick, easy interface; fast results; fabulous filters
Cons: Price performance is only average; doesn’t display baggage and other fees until you click over to book directly from the airline
4: TripAdvisor
#4: TripAdvisor

TripAdvisor is no longer just a place to vent about bad waiters. The granddaddy of travel crowdsource sites is trying to become a one-stop shop for all your travel needs and, we have to admit, once you weed through the pop-ups, its efforts in the airfare search department are pretty impressive. It’s obviously working hard: The two times it found the best prices involved creative uses of stopovers on international flights that no other engine came up with. Also, it never won the anti-prize for the worst result, and the few times it found sub-par fares, it was in good company with all six of the websites ranked below it. It offers a “FlyScore” rating for every flight based on in-flight amenities, duration, type of aircraft, and TripAdvisor reviews.

On the other hand, the fare results on our Top Three were all head and shoulders above TripAdvisor, landing it just shy of the medalists' rostrum at #4. (However, TripAdvisor desperately needs to figure out how to remove ludicrous results, like 10-hour layovers, or offering to fly us from Rome to New York instead of to Philadelphia as we requested. That was so strange that as an extra test, we tried a Philly-to-Salt Lake City search, and TripAdvisor’s top three price results expected us to either accept a 21-hour layover in Denver, a return flight that only made it as far as Kansas City, or—truly bizarrely—a leg that required us to somehow make our own way from the Kansas City airport to Denver International during a 4:37 break in the itinerary.)

Pros: Fast results; fare alerts; vacation packages; decent filters
Cons: Results only average; doesn’t include baggage fees; suggests hare-brained itineraries not worth the savings
3: Skyscanner
#3: Skyscanner

Slipping one place to #3, Skyscanner was one of the first engines to include low-cost airlines (though these days, most do)—and it remains an excellent place to find some of the lowest fares available. Though in our tests it stumbled a few times on last-minute quotes—how did it miss so many direct London–Barcelona flights on Ryanair, easyJet, and Vueling that all the others found?—it did stellar work on fares six weeks out, either tying or beating the results of our #1 site. Add to that its decent filters, a flexible dates “whole month” calendar and graph on every search, the ability to search for destinations in an entire country rather than just one city (you can even type “Everywhere” in the destination field for a list of cheap fares from any departure airport), and our verdict is made clear: We suggest never booking a ticket without checking Skyscanner first.

Pros: Among the best at the lowest fares; shows price for the same flight from multiple OTAs/airline sites; can provide a whole month of fares on a calendar for flexible dates; shows which airline actually operates a codeshare; fare alerts; vacation packages
Cons: Not quite as strong on last-minute flights; doesn’t include baggage fees; clutters organic results with sponsored results (though it marks these clearly)
2: Momondo
#2: Momondo

For the first time since it premiered in 2006, Momondo slips to the #2 spot, but it remains one of the best places to find the cheapest airfares, especially on last-minute tickets (though not consistently). Interestingly, Momondo has transitioned from pure aggregator to an OTA as well, now offering direct booking on its own site. It is admirably transparent about this; when you click the dropdown menu for any deal, it displays its own price first but also includes fares from other sites and the airlines itself that sometimes beat it. Its results screen remains one of the most complete in terms of all the intel it offers in its dashboard—though it would be nice to include actual baggage fees rather than generic notes like “baggage fees may apply” on airlines it knows will charge them. Momondo also offers that fun “Anywhere” option that displays cheap fares from any departure city. 

Pros: Excellent results overall; provides shortcuts to your choice of the cheapest, quickest, or best overall results; nifty fare calendar graph shows average prices for other days (one week before and two weeks after each flight); fare alerts; “Flight insight” data feature for your chosen city pair (the cheapest and most expensive fares, pegged to season, airline, time of departure, day of the week, and more); shows price for same flight from multiple OTAs/airline sites
Cons: Occasionally not the cheapest on price (but usually by only 10% or less); it canvasses so many international OTAs and discounters (a positive) that you do need to do due diligence on unfamiliar airfare-selling outlets before purchasing
The Top 10 airfare search sites: 1: Skiplagged
#1: Skiplagged

All hail the new champion! This upstart debuted in 2013 to exploit “skiplagging,” a somewhat shady savings technique the airlines hate—it involves buying itineraries that have stops and abandoning some flight legs before the final destination. It's important to note that we only included legitimate fares (not controversial skiplagged fares) for our analysis, and this site still won. It has now outgrown its hacker roots to knock Momondo from the #1 perch for the first time in nearly a decade. The results for the top three finishers show you how solid the victory was: #3, Skyscanner: 12 points. #2, Momondo: 13 points. #1, Skiplagged: 23 points. Wow.

In our 25 search scenarios, this aggregator found the lowest price ten times, the second lowest five times, and the worst price never. The only two “bad” rates it found were for last-minute flights involving connections (and it’s worth noting Skiplagged actually found the best fares for direct flights on the same itineraries). It also offered a free-spirited “Anywhere” option for the destination field.

We did have a few criticisms, most significantly that it didn’t let us enter a city name, only airports—for big cities with multiple airports, this will force you to search several times. Skiplagged also lacks robust filters, doesn't disclose baggage fees and such until the end, and rounds down all the prices—that last complaint is minor since we're only talking about a few cents, but just feels sneaky. Its unbeatable price performance surmounted all of those quibbles.

Pros: Price champion; noticeably fast
Cons: Mediocre filters; no flexible dates option (though it does has a graph showing indicative prices over 30 days); shows each leg of an itinerary separately, so you have to keep choosing various legs before you see a total price; doesn’t show baggage fees until you click to book; still sells optional “skiplagged” results that airlines have sued passengers for using (but you can disable this by unticking the "Hidden City" option)