By Chris Morris

PHILADELPHIA (CBS) – On today’s APP-tastic and outta SITE – Hopper.

Saving money on flights is a tough challenge, given how often airlines change fares. The Hopper app analyzes billions of flight prices to tell you the optimal time to purchase.

It’s an inexact science, but it could save you up to 40 percent.

It will also let you know how much it can save you, so you can decide if it’s worth it – or offer better prices on alternative dates.

Check out the Hopper app.