There are now so many websites where you can search for airline tickets that there is hardly any need for more of such sites.
Although most sites work well, it can of course always be better. I recently had a clear moment, I think, and suddenly I found myself in the "flights" section of Google.
Google Flights has been around for a while, but I have to admit that it was new to me. When you search for "flight Amsterdam Bangkok", for example, you will now see the "Flights" option between the "Web, Images, Videos, News", etc. options. Click on that option. Of course you can also go directly to Google Flights: www.google.nl/flights/
Then you are there and you can see for yourself what is possible. One of the interesting things is that after entering a departure date on the calendar you will immediately see the lowest price for every possible return date. You can also save searches. If you call another one later, you will see the price development.
What I often fail at other sites, an overview of the lowest prices of only direct flights per date, is a piece of cake here.
It may not be the only way to make it, but it is not just another search site with only more of the same.