I know that I’m not the only expat that frequently travels between Phnom Penh and Siem Reap and doesn’t bother to book in advance for hotels. Despite what you may hear on various travel forums, even during high season there are more hotels than there are guests and you’ll always be able to find a room, even at the last minute.

Usually, I take advantage of the WiFi on Giant Ibis buses and try and book a room on Agoda as I’m on my way to Siem Reap. They have decent last-minute deals that are worth looking at. But last month a friend showed me a new app that has deeply discounted rates for both Siem Reap and Phnom Penh that blow the other hotel sites out of the water. The catch is: you must book same-day and each booking is only for one night. For expats like me, who often don’t begin thinking about a hotel until I’m halfway across the country, it’s a perfect choice.

The HotelQuickly app gives expats the chance to stay in some of the nicest hotels in Phnom Penh and Siem Reap for one night at a hugely discounted rate, with a guarantee that it’s the lowest price available. If you use a signup code as explained below, you’ll get an additional $15 your first room.

I’ve tried the app a few times and stayed at several Siem Reap hotels and despite some initial difficulties, found it to be easy to use. The phone support leaves a lot to be desired (it’s an offshore call center) but it only took 15 minutes to get a response via email. I booked a hotel and when I walked up to the desk ten minutes later, they greeted me by name and had a print-out of the booking. Hotels use HotelQuickly to sell rooms for the night that would be empty otherwise, which is why the rooms are so cheap, and also why they’ll only let you book a day at a time.

The Siem Reap offerings are especially impressive, and include many of the city’s most well-known 4- and 5-star hotels. What’s available changes every day, of course, but I’ve seen the Victoria Angkor Resort, Heritage Suites, Shinta Mani, Grand Hotel d’Angkor, and various Frangipani properties. There are cheaper hotels, too, in the $15-30 range, but these usually disappear earlier in the day. If you’re looking for something budget, book in before lunchtime.

Phnom Penh seems to have more budget options, with rooms as low as $15 (which is free if you use the MTCAM code, explained below) well until evening-time. They also have fancy-shmancy offerings, including the Raffles Hotel Le Royal when I checked today.

Properties vary day to day, and even hour by hour, so even if you don’t find what you want once, it’s worth checking again later.

To use HotelQuickly, download the HotelQuickly app to your smartphone or tablet. Here’s the link to the Apple store and the Android marketplace.

If you use the code MTCAM to book a hotel room, you’ll get $15 off your first booking (and I’ll get $15 off my next hotel booking). Win-win.