What Are The Best Value For Money Flight APIs You Know?

Hi! I’m working on building my own flight search engine so I don’t have to spend hours searching manually.

The main advantage is custom filtering that I can’t apply on existing search engines, and I’m already getting results that are better than some of the tools currently on the market.

That said, the more data I can pull, the better the results will be—so I have a couple of questions:

• What free flight APIs do you know that offer a generous or unlimited request quota?
• What are the best “bang for the buck” flight APIs you’ve used? (Considering price per request and the size/quality of the data pool.)

Thanks!