Kayak’s iPhone app. — AFP picSAN FRANCISCO, April 20 — A new study by comScore has found that the most popular travel-related smartphone activity is checking airline prices on the go. Here, a round-up of some of the best apps out there.

Kayak

iOS, Android, Nokia, Windows

Available for both iPhone and iPad, Kayak’s meta-search system is one of the best on the market. It’s simple to use and is very slick, offering plenty of options for travelers with tricky itineraries.

http://www.kayak.com/mobile

Hipmunk

iOS, Android

The coolest thing to come out of Silicon Valley in some time, Hipmunk takes the pain out of flight search. Or at least, it ensures that you know about the pain that’s there, ranking flights by how convenient they are (avoiding eight-hour layovers, for example), rather than price, which is a boon for frequent flyers.

http://www.hipmunk.com/mobile

Skyscanner

iOS, Android, Windows

Skyscanner copes well with complex routes and can also handle routes that involve budget airlines where they’re available. The clever price chart allows users to see daily average flight prices.

http://www.skyscanner.com/mobile

FareCompare

iOS

The When-to-Fly app offers real-time alerts on your favourite routes, based on FareCompare’s data, which can take into account your home airport.

http://www.farecompare.com/iphone/download

TripAssist

iOS

This Expedia app provides alerts for any flight for free, as well auto-syncing itineraries booked through Expedia from your account. You can book flights direct from the app and access Seatguru seat recommendations at the same time.

http://itunes.apple.com/us/app/tripassist-by-expedia/id314063730?mt=8. — AFP-Relaxnews