There are so many sites that claim hotel deals. My go to app is Skyscanner for hotels as well. Some of my other favorites:
Trivago.com
Hotwire.com
Booking.com
Hipmunk.com
Orbitz.com
Hoteltonight.com
Momondo.com
Priceline.com
Kayak.com
Expedia.com
Most of these places also have an app you can download off google or the apple store.
If you are looking for an alternative place to stay there is www.airbnb.com or www.hostelworld.com Good Luck!