Viral Growth Loops Hub: PLG, Referral, and Community Mechanics

A viral loop is not a marketing campaign. It is a product mechanic where the act of using the product produces the next user, and the cycle time of that mechanic is short enough to matter. Most products that claim viral loops do not have them. They have referral programs with a coefficient below one, which is a leaky bucket pretending to be a flywheel. The interesting design question is what action inside the product naturally produces an invitation, and how short the gap between value and invite can be.

This hub gathers the math and the product-led patterns we use when a client asks for viral growth. Start with the viral coefficient calculation to set a realistic target. Read the viral-loop design piece for the canonical loop types. Then move to PLG mechanics if your product has self-serve potential, or to community-led growth and gamification if your loop runs on identity and status rather than utility. The CAC-reduction blog ties it back to the unit economics that pay for everything else.