Flying through the major hubs of the big airlines could make your trips more expensive than they should be. Tripdelta finds the hidden airports that could save you as much as 90 per cent over the standard route.
The site was built by a team of mathematicians who travelled to more than 100 countries to find the best airports to connect you to where you want to go. For example, if you're flying from San Francisco to London, tripdelta finds the cheapest route will be from Oakland to Los Angeles and then from LAX to London (LGW). Kayak simply has you go from SFO, which costs $US193 ($267) more.
Tripdelta works best now for one-way flights and there might be a convenience cost, with multiple transfers. Still, if you're looking for the absolute cheapest flight, this is a good place to start your search.