By now, you probably know how to set up price alerts on KAYAK, or find cheap
airline fares via Hopper, but there are also some
lesser-known sites that can help you save a ton of money
on flights.

In addition to the three best websites you should use to find
cheap flights, here are three under-the-radar tools that you
should take advantage of:

First, ITA Matrix is a simple but powerful search engine
that helps you find the cheapest flights.ITA
Matrix.ITA
Matrix

The basics: At first glance,
ITA Matrix is kind of underwhelming, but what the site lacks
in flash, it makes up for in efficiency. Developed by a group of
MIT computer scientists and acquired by Google in 2010, ITA
Matrix is the same software that powers travel search engines
like KAYAK and Google Flights.

To search for flights, just enter your origin, destination, and
desired length of stay. Also, make sure you select "See calendar
of lowest fares" instead of "Search exact dates," so you can
easily see and compare itineraries. For example, if you have some
wiggle room in your travel dates, you might be able to save
a ton of money just by leaving on a Wednesday instead of a
Friday.

When you find a price you like, just click on it, and you'll be
given detailed information that you can use to book the flight
via the airline, a travel agent, or another booking service.

Helpful tips: If you have some time to
spare, and you're dedicated to finding the cheapest flight
possible, you should try playing around with ITA Matrix's
advanced routing and extension codes. These codes help you narrow
down your search and make it easy to find cheap but complex
itineraries.

To use these codes, click "Advanced controls" and then click the
blue question mark icon. A yellow glossary will pop up that shows
you examples of routing and extension codes you can use to filter
your search. For example, if you type in X: NYC, your search will
only show you flights with a connection point in New York City.

How to use ITA Matrix's advanced
codes.ITA Matrix

In addition, since booking multiple one-way flights
can be cheaper than booking a round-trip ticket, don't forget
to try ITA Matrix's multi-city search option. Just click the tab
that says "Multi-city" at the top of the page, and enter your
travel details.

Second, The Flight Deal is a curated collection of
the best deals currently available.

The basics: The Flight Deal's team only
publishes fares that are $0.06 per mile or less, which means
"a nonstop round-trip from New York to Barcelona should never be
more than $425." Just browse through the site and click on a deal
when you find one you're interested in. In addition to details
about fare availability, you'll also see detailed instructions
for how to find the flight on ITA Matrix.

Helpful tip: The Flight Deal also
specializes in finding
mistake fares, or price glitches, that you can book for a
short time before airlines fix the error. Perfect for adventurous
travelers, these deals let you see the world and take spontaneous
trips for a lot less. Just make sure you follow The Flight Deal
on Facebook and Twitter to hear about these mistake fares
right away.

Finally, Skiplagged helps you take advantage of
loopholes in airline pricing.

The basics: Typically, flights to popular
destinations such as New York City are more expensive than those
to less popular destinations such as Hoboken, New Jersey. A
throwaway ticket — also known as "hidden city ticketing" — is a flight you book
to an unpopular destination with a layover in a popular
destination. Then, instead of getting back on the plane after
your layover, you just stay in that city.

It's worth mentioning, however, that Skiplagged was sued by
United Airlines and Orbitz in 2014 for helping customers find
these loopholes in airline pricing. Although the case was thrown out, and exploiting hidden
city ticketing isn't technically illegal, you may still face some
consequences
if you're caught abusing throwaway tickets by a major
airline. While you'll avoid a fraud charge by coming clean, you may still
"receive a written warning [...] be denied boarding, have [your]
ticket confiscated," or be fined for the difference between what
you paid and the "lowest
applicable fare."

Helpful tip: Make sure you
don't book round-trip flights in an attempt to exploit hidden
city ticketing. When you skip a leg of a round-trip itinerary,
the airline cancels the rest of your trip. You also won't be able
to check any bags since they'll arrive in the throwaway city and
not your desired destination.

Bonus: Scott's Cheap Flights sends you a newsletter
of the best international deals, curated by an expert at finding
cheap flights.

The basics: Scott Keyes is a
travel expert who once booked a world trip that spanned 13
countries, all
for free. His website, Scott's Cheap Flights, helps you find the
cheapest international flights available. All you have to do is
enter your email and let Keyes and his team do the heavy
lifting. Once you receive the newsletter, you can use the
information provided to find the same deals on Google Flights.

Helpful tip: While Scott's Cheap Flights is
pretty straightforward, you can also upgrade to a premium
newsletter for $39 a year. The subscription service gives you
access to more deals and lets you customize your newsletter so
you only see flights from select airports.