Referral programs

Referral Programs

Core Mechanics

Referral Program Types

Type	Reward structure	Best for
Double-sided	Both referrer and referee get reward	B2C, SaaS trials
One-sided	Only referrer gets reward	High-margin products
Tiered	More referrals = better rewards	Communities, loyalty
Give-to-get	Referrer gives reward to friend	Gifting, generous brand positioning
Social proof	Public leaderboard, recognition only	Community-driven products

Reward Design Principles

1. Aligned with value: Cash for B2B, credits for SaaS, discount for e-commerce
2. Immediate enough: Reward within 24h of conversion, not 30 days
3. Proportionate: Reward ≥ 10% of CLV for referrer
4. Scalable: Cap rewards or set conditions (e.g., referee must pay)

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Viral Coefficient Formula

K = i × c

Where:
  i = average invites sent per user
  c = conversion rate of invites to signups

K > 1 = viral growth (each user generates >1 new user)
K = 0.5–1 = significant amplification
K < 0.3 = referral adds noise, not signal

Example:

• Average user sends 5 invites
• 20% convert to signups
• K = 5 × 0.20 = 1.0 (break-even viral)

To double K: either double invites sent (UX) or double conversion rate (landing page/offer).

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Referral Funnel

Stage 1: Trigger — Make Referring Easy to Think Of

• Show referral CTA at moments of delight (after first value, after milestone)
• Email trigger: "You love [Product]? Your friends will too"
• In-app: after positive NPS or review prompt

Stage 2: Share — Remove Friction

• One-click link copy
• Pre-filled social share messages
• Email invite with pre-written copy
• WhatsApp / SMS share buttons on mobile

Stage 3: Land — Convert the Referred Friend

• Dedicated referral landing page (not generic homepage)
• Personalized: "Your friend [Name] invited you to try [Product]"
• Urgency: "Claim your [reward] — offer expires in 72 hours"
• Clear CTA above the fold

Stage 4: Activate — Confirm the Reward

• Email confirmation: "Your reward is unlocked!"
• Show reward balance in dashboard
• Notify referrer when friend converts: "Sarah just signed up using your link!"

Stage 5: Loop — Encourage Repeat Referrals

• Progress bar toward next reward tier
• Monthly reminder: "You've earned $X — share again to earn more"
• Leaderboard (optional, if competition is on-brand)

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A/B Testing Referral Rewards

What to Test

Variable	Option A	Option B
Reward type	$10 cash	$15 credit
Timing	Immediate	After 30 days active
Structure	Double-sided	One-sided (referrer only)
Framing	"Earn $10"	"Give $10 to a friend"
CTA placement	Post-signup	Post-activation (day 7)

Significance Threshold

• Minimum 200 shares per variant before concluding
• Use two-proportion z-test for conversion rates
• Primary metric: referred user activation rate (not just signup)

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Fraud Prevention

Common Fraud Types

• Self-referral (user signs up with second email to earn both sides)
• Bulk fake signups from one referrer
• Referral code sharing on coupon sites

Prevention Measures

• Require payment method before reward unlocks
• Flag multiple accounts from same IP / device fingerprint
• Set minimum activity threshold (e.g., 7 days active, first payment)
• Review outliers: anyone with >10 referrals in first week
• Exclude referral reward from first 48 hours of signup
• One reward per email domain (blocks self-referral via work email variants)

Fraud Detection SQL (example)

-- Find suspicious referrers
SELECT referrer_id, COUNT(*) as referrals, 
       COUNT(DISTINCT referee_ip) as unique_ips
FROM referrals
WHERE created_at > NOW() - INTERVAL '7 days'
GROUP BY referrer_id
HAVING COUNT(*) > 10 AND COUNT(DISTINCT referee_ip) < COUNT(*) * 0.5
ORDER BY referrals DESC;

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Referral Program Optimization Checklist

Launch Readiness

• Unique referral link generated per user
• Referral tracking (UTM + cookie + server-side)
• Double-spend protection in place
• Terms & conditions page live
• Reward fulfillment automated (not manual)
• Email flows: share prompt, confirmation, reward delivery

Ongoing Optimization

• Weekly: review K coefficient trend
• Weekly: check fraud flags
• Monthly: A/B test one variable
• Monthly: email reactivation to non-referrers
• Quarterly: review reward economics vs CAC

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Economics Sanity Check

Referral program is worth running if:

  Reward cost < (CLV of referred user) × conversion rate

Example:
  CLV = $500
  Referral conversion rate = 30%
  Expected CLV from referral = $500 × 0.30 = $150

  Double-sided reward = $20 + $20 = $40

  $40 < $150 ✅ Program is profitable

  Also compare: Referral CAC vs. Paid CAC
  If referral CAC = $40 and paid CAC = $120 → 3x more efficient

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Case Study Patterns

Dropbox (Give storage, get storage)

• Double-sided: both get 500MB free storage
• Drove 3900% growth in 15 months
• Reward was the product itself → zero marginal cost

Airbnb (Travel credit)

• Double-sided: $25 travel credit for both parties
• Required first booking to unlock → qualified referrals only
• Fraud layer: payment card required

Uber (First-ride free)

• Referrer gets $5, referee gets free first ride
• One-sided economic risk but high conversion
• Geo-targeted rewards matched to market

Pattern: Most successful programs reward an action beyond signup (first purchase, first key action) to filter for quality.