AI Practice Knowledge BaseAI Self-Growth System
Viral Product Design
PremiumLet the product speak for itself and make users want to share
Viral Product Design: Turn Users into Your Salespeople
"The best ad is 'I am using this too'."
What you will get in this chapter
- Viral coefficient (K) and the breakdown formula
- SOP and friction points of viral loops
- Core metrics for viral growth
One-sentence definition
Viral growth = users bring users.
The key is not "ad spend", but making sharing part of the experience.
Minimum viable viral system (MVS)
| Step | You need | Acceptance result |
|---|---|---|
| Aha moment | Visible result within 30 seconds | Users want to screenshot/share |
| Share trigger | Share button/result card | Share rate >= 5% |
| Receive conversion | Low-friction entry | Share click conversion >= 10% |
Qualified signal: K >= 0.3 (early loop can run).
K factor breakdown (must know)
K = invite_rate * acceptance_rate- Invite rate = sharers / total users
- Acceptance rate = new users / share clicks
Targets:
- Early: K >= 0.3
- Mid: K >= 0.7
- Ideal: K >= 1
Viral loop SOP (standard process)
- See value: get results within 30 seconds
- Trigger share: one-click share / result card
- Receive conversion: enter and use via link
- Experience again: new user hits Aha
Every step has friction. Reduce one step and K improves.
Three types of virality
| Type | Principle | Example | Strength |
|---|---|---|---|
| Intrinsic | Cannot use without sharing | Zoom / collaboration | Strong |
| Incentivized | Share for rewards | Referral bonuses | Medium |
| Word-of-mouth | Product is too good not to share | ChatGPT screenshots | Strong |
Prioritize intrinsic virality.
Common mistakes
- Aha moment too late
- High share cost (screenshot/copy/fill forms)
- Entry too complex (signup/forms)
Fixes:
- Aha <= 30 seconds
- Share button always visible
- Shared link goes straight to experience
Core metrics (must track)
Definition (default):
- Time window: unless stated otherwise, use the last 7 days rolling.
- Data source: use one trusted source (GA4/GSC/platform console/logs) and keep it consistent.
- Scope: only the current product/channel, exclude self-tests and bots.
| Metric | Meaning | Pass line |
|---|---|---|
| Share Rate | Sharers / total users | >= 5% |
| Click-to-Visit | Clicks / shares | >= 20% |
| Visit-to-Signup | Conversions / visits | >= 10% |
| K Factor | Invite rate * acceptance rate | >= 0.3 |
Acceptance checklist
Aha moment <= 30 seconds
Share card and button are complete
Shared landing page allows direct use with no signup friction
Summary
Key takeaways
1. Viral growth is "users bring users".
2. K factor is core, broken into share and acceptance.
3. The faster the Aha moment, the stronger the viral loop.
Next chapter: Shareable Result Patterns - design result cards people want to post.