Before you proceed, you need InTouchApp installed on your phone & InTouchApp Extension installed on Chrome or Firefox. Learn more.
How to bulk save contacts from WhatsApp to Phone:-
Step 1 - Open web.whatsapp.com in the browser and Scan the QR code by using WhatsApp on phone.
Step 2 - Click on ‘SCAN NOW’ button or the red + icon > Find unsaved numbers.
Step 3 - It will scroll through your chats and would detect all the unknown numbers. (Wait for the scanning to complete, detecting all the unknown numbers from your chats.)
Step 4 - Click on SAVE and all Unknown numbers will be saved to your phone as WhatsApp Web 0001, WhatsApp Web 0002 etc. (It may take a while depending on the numbers of unknown contacts and your internet speed.)
*You shouldn't click on SAVE button again unless the first Save and Sync are completed.