WhatsApp’s Click to Chat feature allows you to begin a chat with someone without having their phone number saved in your phone’s address book. As long as you know this person’s phone number, you can create a link that will allow you to start a chat with them. By clicking the link, a chat with the person automatically opens. Click to Chat works on both your phone and WhatsApp Web.
To create your own link, use https://wa.me/<number> where the <number> is a full phone number in international format. Omit any zeroes, brackets or dashes when adding the phone number in international format.
For a detailed explanation on international numbers, read this article. Please keep in mind that this phone number must have an active account on WhatsApp.
Don’t use: https://wa.me/+001-(555)
To create your own link with a pre-filled message that will automatically appear in the text field of a chat, use https://wa.me/
To create a link with just a pre-filled message, use https://wa.me/?text=
After clicking on the link, you will be shown a list of contacts you can send your message to.