@Juliette only skyscanner I'll have a look at the others thank you x
If you're flexible or planning in advance, I love the hopper app. I've gotten some insane deals on there like round trip flights from Salt Lake city to Dublin for under $300
Yes I love hopper too & it’ll tell you when the best time to buy is and approximate price!
Have you tried, Skyscannner Justfly Kiwi