During the election campaign, Labour had a nice site, https://getoutandvote.co.uk that would prefill a WhatsApp broadcast message to send to your mates to tell them to go vote.

The tech is pretty simple, and as we already have our own redirector set up, I’ve made the same sort of thing for us to spread the word at https://havesomenew.io/whatsapp. See what you think, and let me know if you think of better wording.