What’s your favorite alternative?
[1] http://web.archive.org/web/20160413025405/https://developers...
Momondo had to monetize a little in the past year, and now includes a little bit of referral spam, but still produces good results, their sort by “best” feature is usually helpful!
I loved Hipmunk for its personality and “agony sort”, though. Personality is often missing from modern travel brands.