It's that easy:
Installing the Chrome Extension

2. Step
Now start WhatsApp Web in zour browser, open the extension and you can start analyzing your contacts.
Using the extension

Contacts
Here you can analyze your contact network. Just click on "Analyze Contacts" and watch as the network builds. After all groups are analyzed you are asked to download a file with the assignment of the names of contacts and groups. Then a webpage with the analysis opens.