Most people spend months or even years planning trips abroad, but that’s not always an option. Emergencies happen, work calls or sometimes you just get bit by the travel bug. Buying plane tickets on the fly can be stressful, so it’s easy to just accept the first offer you find. After all, you should expect to pay more for booking at the last minute, right?

Believe it or not, airline tickets often become cheaper as the departure date draws near. You can even find first class or business class seats at discounted rates by putting off your purchase. This guide provides an explanation for how airlines set their fares, as well as an overview of the many websites that purport to offer outrageous last-minute deals for flights around the world.

How Plane Tickets Are Priced

It’s logical to assume that buying plane tickets far in advance guarantees you the best price, but you’ve likely seen websites advertising last-minute flight deals at unbelievable prices. You’ve also likely noticed that flights between the same destinations on the same day and even on the same airline can vary by hundreds of dollars. Why does the cost of flying fluctuate so widely?

Airline companies essentially auction off their seats. Therefore, whenever you search for plane tickets online, you’re participating in an auction. An initial price, or “published fare,” is set for each flight based on previous supply and demand, but the price can climb as the flight fills up. If tickets aren’t selling well, the price can actually go down. When flights have just a few seats left, carriers sometimes contract with companies to sell the unsold seats at a discount. Since the advent of the internet and search engines, aggregate websites that let you search for the best deals being offered by different companies have become increasingly popular.

That’s how savvy flyers are able to score first class seats without paying first class prices. What kind of magic is required to find such deals? Truthfully, there’s nothing magic about it; you just have to know where to look. Below is your guide to the many websites that specialize in helping travelers find cheap last-minute airline tickets and travel packages:

Best Websites for Booking Last-Minute Flights

IFlyFirstClass.com

As the name implies, IFlyFirstClass.com caters to customers who are tired of flying coach. The company’s flight consolidator database lets travelers search for discounted first class and business class seats on most major US and international airlines. The website boasts that customers can save up to 60 percent compared to the fares published by airlines.

Some tickets may be exchanged or refunded, and the company offers 24/7 customer service. The website has a handy tool that helps you determine if you need a travel visa for where you’re going. With a 9.48 out of 10 rating on ResellerRatings.com, it’s difficult to find a negative review of IFlyFirstClass.com.

FlyWorldClass.com

FlyWorldClass.com has contracts with several airline ticket consolidators and wholesalers. According to the website, flyers can save an average of 20-50 percent over published fares. Although the prices you see advertised represent the total cost, be warned that your credit card will show two charges: one for the base fare, and another for taxes charged by the airline. Many tickets can be changed for a “minimal fee.” Thanks to their stellar deals and customer service, FlyWorldClass.com currently holds a 9.7 out of 10 on TrustPilot.com.

CheapFirstClass.com

Rather than operating like a search engine for cheap flights, CheapFirstClass.com works like a traditional travel agency in that they offer highly personalized trip planning. After users “request a quote,” a customer service representative contacts them via email with the best offers. You can also call in for an even more personalized experience.

The company claims that their prices average 30-70 percent cheaper than published prices. Customer service reps basically research and compare prices offered by other companies to determine the most affordable option. Thanks to their exceptional customer service, CheapFirstClass.com currently has a 4.5 out of 5 on Yelp.

LastMinute.com

In addition to letting you book flights with over 400 domestic and international airlines, LastMinute.com can hook you up with sweet deals on hotels and other accommodations. The company claims to have established strong relationships with airlines and hotel chains over the past decade, which is how customers are able to save up to 35 percent over published prices on flights and rooms.

LastMinute.com also offers more than 40 million dynamic holiday packages, but online reviewers have complained about the company’s cancellation policies, subpar customer service and even inconsistencies between advertised prices and actual charges. Consequently, LastMinute.com has just a 6.6 out 10 rating on TrustPilot.

FareBoom.com

If you haven’t heard of FareBoom.com, that’s because they don’t advertise. As a result, they can afford to sell plane tickets at cheaper prices than their competitors. This approach has kept the family-owned business afloat since 2002.

Depending on which airline you choose, you may be able to select your seat via the handy seating map. Since they run a relatively bare bones operation, FareBoom.com doesn’t provide guidance for obtaining travel visas like some of the other websites listed. Nonetheless, the company has an 8.9 out of 10 rating on TrustPilot, and most of the negative comments come from travelers who didn’t bring the appropriate paperwork required for their destination. It’s always the responsibility of the passenger, not the airline or travel agency, to make sure they obtain all necessary travel documents.

1st-Air.net

As mentioned earlier, buying a plane ticket is like participating in an auction. 1st-Air.Net aims to bring transparency to the process so that customers know if they’re getting a fair fare.

To you purchase through 1st-Air.Net, you must sign up for a membership. While this will be a deterrent to many, membership gives you access to pricing analysis, which lets you know if fares are expected to increase or decrease in the near future. That said, unlike most other companies on this list, 1st-Air.Net is not accredited by the Better Business Bureau, nor does it have a score on TrustPilot. It’s a terrific resource for information, but purchase tickets at your own risk.

Priceline.com

Priceline.com has been around for a long time. The William Shatner-endorsed company has been helping customers find last-minute flight deals since 1997, so their reputation is well established.

The company promises savings up to 50 percent over published prices. If you book tickets one week in advance, you can take advantage of the Name Your Own Price feature. Their selection of affordable flights, however, is somewhat limited. You can catch some excellent deals on select locations at specific times, but you may get more consistent savings elsewhere.

CheapFlights.com

The homepage of CheapFlights.com is very welcoming, but navigating the website can be a bit tedious. Fortunately, the website lets you compare prices with similar websites like CheapOair and Priceline, so you’re bound to encounter some good deals along the way.

To get a good fare from CheapFlights.com, you have to book about two weeks in advance, so it’s not the best choice for very last-minute flights. Their special offers, however, are a real steal if you want to book a vacation on the fly. The website also has helpful information about the best time to visit different parts of the world.

TravelZoo.com

Similar to Fareboom, TravelZoo is relatively bare bones. The homepage isn’t cluttered with graphics and blog posts; the first thing you see is a search bar. Just type in a city and search “all deals.”

Unfortunately, that’s when things start to go downhill. Users get re-routed to other platforms like Travelocity and Expedia. If you don’t have a pop-up blocker enabled, you’re likely to get bombarded by new windows. TravelZoo basically fetches the best deals from other websites, so it’ll give you plenty of options, but it may be easier just to search each site individually.

Kayak

Kayak has been around a while, so their reputation continues to hold up. Their website is refreshingly easy to navigate. Nonetheless, like TravelZoo, it simply aggregates deals from third-party sites. That said, Kayak also finds deals on hotels, car rentals and cruises, which sounds slightly ironic. Signing up for the Kayak “price alert” feature is well worth a minute of your time since it will notify you when insane last-minute deals arise.

Expedia

Expedia appeals to globetrotters, which is why they provide full service in English, Spanish and Chinese. Expedia’s partnerships with airlines, hotels and car rental companies all over the world have made them the go-to website for affordable travel packages. They don’t specialize in last-minute flights, but you can catch some impressive deals on their website.

Anyone can purchase flights through Expedia; however, if you elect to join, you get access to special offers and their rewards program. Of course, you should expect your inbox to be flooded by promotional emails. If you’re willing to wade through it all, you’ll find some real steals. To encourage use of new technologies, the company awards extra point to users who purchase through the Expedia app.

Travelocity

If you think the Travelocity website looks eerily similar to Expedia’s, that’s because they are owned by the same company. Travelocity is essentially a wing of Expedia that focuses on last-minute travel plans. That said, Travelocity boasts some unique features.

When you sign up, you’ll be asked questions about your travel habits and budget. This information helps Travelocity provide you with personalized, daily travel deals. Members can also score an automatic 10-percent discount on certain hotels. Anyone who likes to travel on a regular basis should definitely keep their eyes on Expedia and Travelocity, but don’t neglect to search for better deals elsewhere.

AirfareWatchdog

As soon as you arrive on the AirfareWatchdog.com homepage, you’ll be presented with impressive rates for flights from your local airport to destinations across the US. The bottom of the page features links to suggested itineraries for planning bargain vacations around the world.

AirfareWatchdog is another aggregate site, so it simply compiles the best prices from other websites. Their selling point is that they have a staff of analysts. In other words, AirfareWatchdog isn’t just a search engine that depends on algorithms. There are humans behind the scenes searching for the best deals and blogging about them. It’s a great tool for comparing prices, but you’ll ultimately have to book with a third party.

Hipmunk

Booking flights can be a stressful experience, especially if you’re making last-minute decisions. Hipmunk aims to put travelers at ease with its adorable mascot and the tagline “Don’t let planning travel drive you nuts.” If you sign up, you’ll receive regular travel tips from a cartoon chipmunk sporting aviator glasses.

Since Hipmunk is very app-driven, it’s super convenient for buying plane tickets via your smartphone. You can link your Hipmunk account with Facebook Messenger and Skype to receive notifications or contact customer service through those platforms. Like Kayak and AirfareWatchdog, Hipmunk simply aggregates the best offers from websites like Expedia and Priceline.

AirTravelGenius.com

AirTravelGenius.com isn’t a search engine or a travel agency; it’s just a blog with tips for finding bargain flights. That said, it has a wealth of valuable information about current trends in ticket prices, so if you’re a world traveler, then you must follow AirTravelGenius.com.

First Class vs. Business Class

Some people mistakenly use the terms “business class” and “first class” interchangeably, but many airlines make a distinction between the two. For airlines that offer both, first class typically offers more amenities. That said, the amenities for first class also differ from airline to airline. Before buying a business class ticket, be sure to check what “business class” entails so that you know exactly what you’re paying for.

Before You Fly

Before you buy a plane ticket, make sure you have everything you need to travel. You’ll need a passport to enter other countries, and some countries even require tourists to purchase a visa. Domestic flights typically require a government-issued photo ID. Obtaining these documents can take weeks or even months, so plan accordingly. Some nations have strict travel restrictions; for example, if you fly to Canada, you might be turned away at the airport if you have a criminal record in the U.S.

Check with airlines to make sure you know what you can and can’t take aboard. If you take medications, make sure they are in a bottle with your prescription information. Some of the websites mentioned above provide customers with this sort of information, but it’s ultimately up to you to make sure you’re ready for takeoff. You may also want to consider purchasing traveler’s insurance in case there’s an emergency.

It’s also important to note who you’re actually buying from and who you should contact for customer service. Let’s say you search for deals on Hipmunk, end up on Expedia and book a flight with American Airlines. Expedia would be your primary contact for most customer service help, but Expedia may refer you to American Airlines for specific issues.