"Build it and they will come" is a myth. Indie developers need to engineer growth into the product from day one. This guide covers growth loop design, referral mechanics with real Dart code, UTM attribution, and analytics setup — all things you can ship in a weekend. 1. Growth Loops vs Funnels A funnel is linear and leaky: Ads → Landing page → Sign-up → Paid. When users drop off, growth stops. A growth loop is self-reinforcing. User actions produce more users. Content loop example: User creates content → Shares it publicly → New visitor sees the content → Signs up and creates content → Loop repeats Enter fullscreen mode Exit fullscreen mode Loop Type Example Key Mechanic Viral / Share Figma share links ShareCard, social posts Content Notion public pages SEO, OGP previews Referral Dropbox "invite a friend" Two-sided reward Product-led Slack free tier Freemium + upgrade nudge 2.…