Which languages booking.com, priceline, hotels.com, expedia.com used and for which purposes?

Which languages booking.com, priceline, hotels.com, expedia.com used and for which purposes?

I have found few info from chatgpt and w3techs. Are there any tools to detect that which languages they used for which parts?

>Are there any tools to detect that which languages they used for which parts?
Probably. But you can also check if they posted any job offers on linkedin or in the website itself, if they grow in size they will probably hire more developers trained in the stack they are using.

If that fails, you will have to read the source code and/or monitor the network.

>booking.com
I found bui-react.css, a library for React, in the Sources so it must be using React for the frontend.
Not sure about what's using in the backend. It seems to be a monolithic application (it sends all params via urlencoded args).

>hotels.com and expedia.com
Node in the backend with Graphql.