The Official WhatsApp Link Format
Number only: https://wa.me/919876543210. With a message: https://wa.me/919876543210?text=Hello%20there, where spaces and symbols are URL-encoded. Message only, no number: https://wa.me/?text=Hello. The older https://api.whatsapp.com/send?phone=…&text=… format also works, but wa.me is shorter.
Common mistakes: a + or spaces in the number, a 0 before it, the country code missing, or a message with raw spaces and & signs that cut the text short. Fill in the boxes above and the link comes out in the right format every time.