Open a waitlist where referring friends moves you up the queue, so the launch markets itself.
Robinhood put up a one-page site for its commission-free trading app long before the app existed. Each person who joined saw their place in the queue, and referring friends moved them up it. Co-founder Vlad Tenev said about 10,000 people signed up on the first day, more than 50,000 in the first week and almost a million within about a year, and the app launched in March 2015, almost a year and a half after the site went up (Business Insider interview, 2017).
By May 2014 the list was about 300,000, with more than 1,000 joining a day (Lloyd Melnick, 15 May 2014).
Consumer apps, fintech, SaaS and physical products with a launch date or limited stock.
Scarcity plus a visible referral mechanic: every sign-up is given a reason and a tool to recruit the next one. Superhuman ran the scarcity half of it, staying invite-only at $30 a month with a waitlist of about 180,000 in June 2019 (Product Hunt, 27 June 2019) and more than 275,000 by February 2020, according to its founder Rahul Vohra (TechCrunch, February 2020).
Self-reported. Robinhood's figures from co-founder Vlad Tenev (Business Insider, 2017) and Superhuman's from its founder. Reported. Lloyd Melnick's analysis of the Robinhood waitlist (May 2014).
Cost to test. A landing page with a referral tool, a few hundred dollars at most.
Kill it if after a month fewer than one in five sign-ups has referred anyone.
Sign-ups are not users: Robinhood has not said how many on its list became customers. A waitlist for a product that never ships burns the list, and fake scarcity gets called out. It works best for consumer products and weakest for large B2B sales.
Seed the Connectors, The Two-Sided Referral, Data PR
A 30-minute call first. If it fits, two calls in one week and a written growth plan you keep.