Google will cut off its airfare data feed next spring, the company quietly announced in its QPX Expr

Google said the service will end on April 10, 2018, and that no new users can sign up. Customers that have already signed up can continue to use until the specified date. The company is now lowering usage fees from $0.035 down to $0.02 per query, after surpassing the free quota of 50 queries per day.

The service first launched in 2011 after Google acquired ITA Software, a flight information software company, for $700 million. Customers of QPX include big names like Bing Travel, Cape Air, CheapTickets, Kayak.com, Orbitz, Alitalia, American, ANA, United Airlines, US Airways, and Virgin Atlantic, according to TechCrunch. It’s not clear yet how Google’s move will affect those platforms.
Google Emails Customers To Look For Alternatives

Google reportedly sent an email to QPX Express API customers telling them to start looking for alternative solutions.
The email was uploaded by HackerNews on Tuesday:

After careful consideration, we've decided to shut down the QPX Express API as of April 10, 2018.

How this affects you
After April 10th, you will not be able to access the API and will no longer be charged for this service. Until then, you will be charged a reduced rate of $0.02 per query for any queries beyond the 50 free daily quota.

Next steps
You don't need to take any action. However, if you are actively using this product you may want to find an alternate solution before April 10, 2018. If you have any questions about these changes, please don't hesitate to contact us at any time.”

Google did not recommend alternatives, but customers might turn to other services like Fareportal, Skyscanner and Skypicker.
Google’s decision to shut down the service comes after the company added the Flight Insights tool, to its Google Flights search service this year. The tool allows users to see when route prices will likely go up and when current air fares will expire.