Built‑in virality - Each new user is encouraged to invite more users, creating a viral loop.

Trust factor - People trust recommendations from friends far more than ads. Referred customers are also more loyal and have higher lifetime value.

Cost efficiency - Instead of paying for ads, you “pay” in product credits or features, which cost you little but carry high perceived value.

Offer the right incentive – Reward both sides with something integral to your product (extra storage, premium features or credits). Avoid cash if it eats into your margins.

Make sharing easy – Prompt users to refer at high‑engagement moments (post‑purchase, milestone achievements) and provide ready‑made share links.

Promote everywhere – Feature the referral program prominently on your website, email footers and onboarding flows. Remind users about their referral status in dashboards and emails.

Track and optimise – Use referral software or simple tracking codes to monitor sign‑ups. Test different incentives, messaging and share channels.

PayPal – One of the pioneers of the double‑sided referral. Early customers got $10 for signing up and another $10 for each referral, fuelling exponential growth.

Airbnb – Offers travel credits to both hosts and guests when a referral leads to a booking, generating millions of users.

Morning Brew – The newsletter rewards readers with exclusive merch and additional content for referring friends, helping it grow from thousands to millions of subscribers.