Airfare forecasting app Hopper is partnering with several airlines to offer “secret” fares at up to 35 percent off what they cost on any other site or app. The new feature, announced Wednesday, could save travelers up to $500 on longhaul flights, according to Hopper.

For example, a flight from New York City to Paris listed at $1,017 round-trip on major search engines was available as a “secret fare” for only $519 round-trip. And a flight from Chicago to Tokyo, listed at $1,422 online, was available for $1,152.

Hopper secret fares
Credit: Hopper

Anyone who has spent a significant amount of time looking for and buying flights online might be thinking this sounds too good to be true. But according to Dakota Smith, head of growth and business at Hopper, “being a mobile-only, closed environment puts us in an extremely unique position.”

Although it's in a competitive market, Hopper has distinguished itself as a great app for tracking and booking flights. The mobile app, available on Apple and Android, sends alerts for trips you're watching, and has recently added hotel price alerts as well.

“If an airline offers these kinds of discounts online, it typically results in a fare war because it’s easy for competitors to spot the discount and price match,” Smith wrote. But Hopper is a closed platform with direct access to travelers that are watching flight prices, so “by offering Secret Fares on Hopper, airlines are able to reach a valuable audience via a private communication channel and secure bookings months ahead of departure.”

To launch, Hopper is offering the cheap flights on more than 60,000 routes. The initial airline partners include Air Canada, LATAM, Turkish Airlines, WestJet, Copa, and Air China, so — at least at first — international flights may be the most obvious place to save.

If you haven't yet booked your summer vacation (you should get on that, by the way), or if you're looking to save on a flight next fall or winter, it's probably time to download this app.