HOW TO IMPLEMENT & MEASURE VIRAL LOOPS: STORIES FROM SAAS GROWTH EXPERTS

Summary from the TLDR Marketing newsletter

The most sustainable viral loops in SaaS come from invites the product already requires, not from asking users to refer someone. A QR code generator labels every free code so each real-world scan exposes the brand, while an assessment tool reaches new users whenever a recruiter invites a candidate. K-factor sums every loop into one growth rate, and the useful inputs are invite-accept rate and invitee activation rather than opens or clicks. Gating rewards on activation and fixing activation first keep the loop fueled, since users who never reach value have nothing to share.