Updated: Apr 8, 2021
Beta tester have early access the some feature before rolled out to everyone. But beta feature may be have some issue.
Whatsapp give new feature access to beta users before rolled out public update.
Whatsapp offers two ways for join beta program
Open your browser and goto whatsapp beta test join page by click this link.
Then click the "Become a tester" button.
Then open playstore in your mobile and search like whatsapp. Whatsapp application showing like "WhatsApp Messenger (Beta)". Install it and join beta test program.
If you want to leave from beta program just goto this link and click "LEAVE THE PROGRAM" button.
Open playstore in your mobile and search whatsapp. Then scroll down the screen you can see the "Become a tester" view with "I'M IN" button. Just click the I'M IN button. Now showing join alert window. Then click JOIN button.
If you want to leave the beta program just follow above instructions and click the "LEAVE" button.