What is the cheapest app to use to buy international air tickets?

The cheapest way to buy air tickets may vary from person to person, and different travelers may have different needs and preferences. However, usually, flight booking software that is easy to use, widely available, and offers affordable prices can help you save money.

Some popular flight booking software are:

1. Ctrip: China’s largest travel website, providing a variety of travel products, including air tickets, hotels, car rentals, etc.

2. Qunar: China’s largest air ticket booking website, providing a variety of flight information and prices.

3. Fliggy: China’s largest travel platform, providing a variety of travel products, including air tickets, hotels, car rentals, etc.

4. Expedia: The world's largest travel website, providing a variety of travel products, including air tickets, hotels, car rentals, etc.

5.Kayak: The world's largest travel price comparison website, providing a variety of flight information and prices.

The above are just some examples, actual conditions may vary by region. In order to get the best air ticket prices, it is recommended that you conduct multiple comparisons and research before purchasing air tickets and choose the booking software that suits you.