Aktarer Zarman's site allows passengers to find the cheapest possible fare through so-called "hidden city" ticketing.
Essentially, it takes advantage of the fact that it can be cheaper to buy a one-way ticket to a random city, with a layover in your actual destination, than simply flying straight there - passengers simply abandon their journey halfway through.
But United and Orbitz have complained about the site, saying they've lost $75,000 in income because of it.
Zarman started a crowdfunding campaign on US site gofundme.com to raise legal fees, saying Skiplagged's "sole purpose has always been to help you become savvy travellers".
We have been... exposing pricing inefficiencies for air travel, among other things.... Everything Skiplagged has done and continues to do is legal, but the only way to effectively prove this is with lawyers.
The airlines argue hidden city ticketing is banned on booking sites - airlines have even stripped passengers found to be using the system of tickets and air miles.