I always get questions asking for the best websites to find cheap flights. I know that everyone is hoping there's a magic site that they haven't heard about yet that will have all of the cheapest flights in one place (me too). Unfortunately, that's not the case. Finding flight deals is hard work and unfortunately, there's no magic site. I usually spend quite a bit of time searching multiple websites before I make any decisions. Below are some sites that I like to use when planning both US-based travel and international travel.
Fare Matrix by ITA
The Fare Matrix by ITA software can be used for both US and international flights. It's a powerful flight search tool that is often used by professionals like travel agents to find the best flight deals for a given routing. With the Fare Matrix, you can also set a starting point and and end point, choose a length of stay and set the system to search +/- two days and it will spit out the cheapest dates to buy your flight on. When you're getting ready to drop $1000+ on an international flight, it's a great idea to check the Fare Matrix and see if you can get a cheaper flight by flying out on Thursday instead of Saturday.
If you would like any additional information on how to best take advantage of Fare Matrix's features, check out this guide from The Flight Deal and also this post from Hack My Trip.
I'm sure most of you have heard of and used kayak.com, so this one should be no surprise. I like to use Kayak to do a general airfare search to determine which airline might have the best deal, then I love that Kayak sends you directly to the airline's website to make the booking.
I've made the mistake in the past of booking directly through sites like orbitz.com or priceline.com only to have a problem with my flight and have the airline not want to do anything about it since I didn't book through them. My recommendation is to always book flights directly through the airline unless it's absolutely impossible (i.e. flying multiple carriers for a long trip and can't find the same deal on the airline's website).
What I like most about Kayak is their price trend and purchase recommendations. Overall, I've found these to be pretty accurate and I think they are helpful when you're trying to make a decision about whether to purchase now or wait. There's nothing worse than booking a flight only to find the price dropped by $50 two days later! I'll check this feature and then set a price alert if it advises me to wait to buy.
What I really like about Google Flights is the map you're presented with once you put in your departure city and dates. I know I want to go somewhere for the weekend of July 4th, but I really don't care where (I just want it to be cheap and to earn a lot of miles). Based on the map, I might choose Chicago for $381.
Another great feature of Google Flights is the subtle hint it gives you regarding the best way to save money with your preferred booking. Once I selected Chicago as my destination of choice, I was presented with a list of fares below a tip that I could save $81 by returning on Saturday instead of Sunday.
You can also get a nifty little graph to pop up with a visual representation of the dates with the lowest fares.
I played around with Momondo when I was planning a trip to the UK earlier this year and I was pleasantly surprised. This site is definitely a great one for searching for intra-European travel and often gave results that I was definitely not seeing on Kayak. Ryanair, anyone?
My favorite thing about Momondo is the calendar visualization at the top of the page. Similar to Google Flights, but a bit more colorful, the graph helps you see which date might have the cheapest fares. I don't know about you, but when I plan international trips, I try to book my incoming and outgoing flights first and then figure out the lowest prices by finagling the dates for each destination.
I honestly don't have a lot of experience with vayama.com, but I wish I had known about it last November when I was trying to book flights to Peru, Bolivia, and Colombia! Since I was trying to book SFO > LIM > CUZ > LPB > BOG > SFO, I was relegated to using cheaptickets.com to book all flights together and it was definitely a pricy experience!
Vayama is primarily branding itself as a site best for booking international travel, so it's definitely worth checking out if you're booking international travel.
There are plenty of other sites I didn't cover here, so it's really all about what works best for you. As I mentioned before, there's no magic site and I would never recommend checking only one site and booking immediately. Picking the right flight is a long, agonizing process and I wouldn't want you to miss out on any of the fun! ;)
Just a twenty-something with a full-time job and a full-time obsession with traveling. It's best to LiveTraveled.