It is very important to know what technology behind a web app before going against it. Like it would be totally worthless to run a Dirsearch to look for files with .php extension if the used technology is actually ASP.NET. So in this tutorial we will learn to use a simple tool called Whatweb to find the technology behind a web app.

Whatweb is pre-installed in Kali Linux, to see the help of this tool run following command in terminal :

The screenshot of preceding command is following:

Screenshot from 2019-01-02 21-43-19.png

The domain name can be as a parameter, or a multiple domain names can be entered by using a --input-file argument:
whatweb example.com

The following screenshot shows output of the command against Facebook.

Screenshot from 2019-01-02 21-52-14.png