If you need a free script for WhatsApp you have a solution with WidgetWhats.
What we give you is a script like this one:
<script async data-id="15144" src="https://cdn.widgetwhats.com/script.min.js"></script>
The script is linked to your domain so is secure to use and will give you all the features you need to have a great WhatsApp Chat Experience in your website.
You can create your account today and start using this free Script today.