I'd use Hipmunk more often if they actually fulfilled their functionality promise as an aggregator. A pretty UI isn't enough.
Sometimes there is an explanation (e.g. the flight doesn't exist, or has a 30hr layover), and other times we don't have the flight, in which case we want to alert our providers to fix it.
- Consolidators [that you don't have commercial relationships with] have wholesale arrangements with airlines allowing them to sell tickets below the direct/GDS price. I suspect you're more reliant on ITA results than many other portals or meta-search sites and their prices are trivially easy to beat on competitive routes if you have a broader range of partnerships.
- Some consolidators put together logical itineraries not bookable via GDS or even direct with the airline. As an extreme example I once bought a cheap, logical pair of connecting long haul flights with Saudia via eBookers that Saudia's website wouldn't allow me to book at any price direct with them; I'd guess the airline didn't want to market anything involving a 5 hour layover in an under-redevelopment terminal in Riyadh. There are plenty of less glaringly obvious potential indirect itineraries that consolidators (potentially including Kayak as well as their affiliates) can identify with Innovata's minimum connect time file and schedule data[1] and other providers might have a more liberal view on reasonable connections than ITA
- Sometimes other sites' metasearch results' advantages are purely illusory, based on outdated results they've cached or screenscraped. I find Skyscanner LCC prices are frequently out of date, even though the actual ticket price is also usually cheaper than ITA's. Other sites might also create the appearance of more choice by not combining codeshared flights into one.
As for LON-SYD on Monday Kayak has a lot more results under $1000 than you. It's possible their much cheaper ticket prices with SIA are outdated or geolocation specific, but the cheapest flight they show (a Garuda two-stopper that's no more obviously agonising than your cheapest result but 10% cheaper) doesn't show on your engine at all. Then again, the price with Kayak had risen to only 5% cheaper than your best price when I started the booking process...
[1]disclosure: I sell that data, amongst many other things, although not to OTAs
But when I clicked on the button to book, the price was different (higher) on the airline website.
(source: was a Skyscanner employee for a bit.)
Every time I've booked a flight in the past couple years, I've gone to Hipmunk to check schedules. Out of the 10 or so flights I've taken, Hipmunk always provided the same prices flights that were important (cheapest/most convenient for me), but I can't say I bothered to look for things that weren't convenient. These were always major airport to major airport things in the US, however.
It does immensely suck that you leave Hipmunk to actually buy the tickets. I had to redo my entire search and purchase because the Safari view of Delta's website in the ipad Hipmunk app crashed.
I also had to recently buy my cross-country Christmas tickets through Expedia. For whatever reason Expedia had far, far better selection and prices. Usually Hipmunk is great but in this case it wasn't even close. That's definitely made me slightly wary of it for the future.
All things said it's great. Can't wait to see where it is in a few more years.