I found the website I was looking for – Kelkoo!

“Kelkoo is a one-stop shopping service, which helps shoppers to find,
research and buy products online with confidence. We provide shoppers with
essential tools to compare prices and product features in

I was excited because Kelkoo searches all of the following airlines, and I thought, “wow, how useful, instead of me trying to go to all these different websites, Kelkoo will do it for me.”