I used to use Hipmunk to book flights but they were recently shut down by the giant enterprise software company that bought them a while back. I went to their URL on a whim and was redirected to a statement from the enterprise software company:
"Why is SAP Concur retiring Hipmunk and Concur Hipmunk?
Simply put, our approach to providing integrated T&E management has evolved."
That "simply put" is doing a lot of heavy lifting