Wadm.me is a website which allow you to create Whatsapp Click-to-chat link with your prefer custom name. Just choose your country code from the list, enter your mobile number without country code. (Eg. 60123456789, just enter 123456789) and default message. The link will auto generate and you can put the link on social media or website, the users will able to chat with you via Whatsapp without save your number to their contact.
DISCLAIMERS: Wadm.me is a third party website and not associated nor endorsed by WatsApp which is registered trademark of WhatsApp Inc. Wadm.me is using official WhatsApp API to send a message to any contact who is registered with the app.