As part practice, part to fulfill a personal need, I have created a no-frills, minimal flight search engine that can be run locally, using the QPX Express API. https://developers.google.com/qpx-express/

The script might be useful for those who - like me - basically procrastinate by searching for flights on a daily basis, but who don't necessarily need to book a flight instantly. Unlike any other web search engine for flights that I know of, my script shows the fare class for each result right away - which can come handy for those who like to optimize for mileage earning.

You find a Readme with instructions, the script and a screenshot here: https://github.com/martinweigert/minimal_flight_search