Cross-Platform Insights: Unify Your Substack and Gumroad Audience into a Single View

80% of your customers are invisible. Here's the AI prompt that reveals who they are and what they're worth

80% of creators can’t see their highest-value customers because Substack and Gumroad don’t talk to each other.

After analyzing my cross-platform data in StackContacts, I discovered:

• 80.09% of my Gumroad customers (736 out of 919) have never subscribed to my Substack

• These “direct customers” find my products through Substack post links, Google, or referrals—then buy without subscribing

• Only 19.91% are subscriber-customers with full engagement data

• But those subscriber-customers spend 33% more ($19.60 vs. $14.70) and engage with 17.55 posts on average

This means:

1. I’m missing engagement data for 80% of my customers (can’t nurture, can’t upsell effectively)

2. I’m leaving money on the table (if all customers engaged like subscribers, average LTV [life-time value] jumps 33%)

3. My Substack content IS working—31% of direct customer sales come from Substack links—but I’m not capturing those leads as subscribers

Imagine if you could unify both platforms into a single customer view. You could:

• See which Substack content drives Gumroad sales

• Identify high-value customers to convert into engaged subscribers

• Calculate true customer lifetime value across both platforms

• Target repeat purchase campaigns to your most engaged subscribers

• Find “dark customers” who bought but never engaged (massive untapped upside)

Let’s dig into your StackContacts data and build that unified view.

The AI Prompt: Copy-Paste Ready

Ready-to-Use StackContacts AI Prompt

Copy this prompt and paste it into Claude (Cursor IDE or Claude Desktop) connected to your StackContacts database.

Using my StackContacts tool, I want to unify my Substack and Gumroad audiences into a single customer view to understand cross-platform behavior and lifetime value.

Please run these analyses:

1. **Email Matching & Overlap Analysis**
   - Count distinct emails in subscribers_detail (Substack)
   - Count distinct emails in gumroad_sales (Gumroad)
   - Find matched emails (present in both)
   - Calculate:
     * Total Substack subscribers
     * Total Gumroad customers
     * Matched emails
     * % of customers who are subscribers
     * % of subscribers who are customers
   - This shows platform overlap

2. **Customer Segmentation by Engagement**
   - For each Gumroad customer, determine:
     * Do they have a Substack profile? (exists in subscribers_detail)
     * Do they have engagement data? (exists in subscriber_events)
   - Segment into:
     * Full Data (Subscriber + Engagement)
     * Subscriber Only (No Engagement)
     * Gumroad Only (No Substack)
   - For each segment, show:
     * Customer count
     * % of total customers
     * Average spend per customer
     * Average posts engaged (if applicable)
   - This reveals data completeness

3. **Customer Lifetime Value by Purchase Behavior**
   - Group customers by:
     * One-Time Buyer (1 product, 1 purchase)
     * Repeat Single Product (1 product, multiple purchases)
     * Multi-Product (2-3 products)
     * Power Customer (4+ products)
   - For each segment, calculate:
     * Customer count
     * Average number of purchases
     * Average LTV (total spent)
     * Average customer lifespan (days from first to last purchase)
   - Sort by average LTV (highest first)
   - This shows who your best customers are

4. **Engagement-LTV Correlation**
   - For all customers, calculate their Substack engagement level:
     * Highly Engaged (50+ events)
     * Moderately Engaged (10-49 events)
     * Lightly Engaged (1-9 events)
     * No Engagement (0 events)
   - For each engagement level, show:
     * Customer count
     * Average purchases per customer
     * Average unique products purchased
     * Average LTV
     * Average posts engaged
   - Sort by average LTV (highest first)
   - This proves whether engagement drives spending

5. **Content-to-Product Affinity Mapping**
   - For customers who engaged with Substack content before purchasing:
     * Identify which posts they read in the 30 days before buying
     * Group by product purchased
   - Show:
     * Product name
     * Post title
     * Number of buyers who read this post (min 5 buyers)
     * Total engagement count
   - Limit to top 30 product-content pairs
   - This reveals "gateway content" for each product

6. **Channel Attribution for Direct Customers**
   - For customers who are NOT Substack subscribers (Gumroad-only):
     * Analyze referrer field to see where they came from
   - Group referrers into categories:
     * Substack (Post/Note Link)
     * Twitter
     * Google Search
     * Direct/Unknown
     * Gumroad Library
     * Other Referrer
   - Show:
     * Traffic source
     * Sales count
     * Unique customers
     * % of direct sales
   - Sort by sales count (highest first)
   - This shows how non-subscribers find your products

7. **Top Customer Engagement Analysis**
   - Identify top 50 customers by total spend
   - Group into tiers:
     * VIP ($100+)
     * High Value ($50-99)
     * Medium Value ($20-49)
     * Low Value (<$20)
   - For each tier, show:
     * Customer count
     * Average spent
     * Average purchases
     * Average posts engaged
     * Average engagement events
     * Average link clicks
   - This reveals behavior patterns of your best customers

Please format results as clear tables with insights after each analysis.

Step-by-Step Instructions

1. Identify Your Database Schema

Confirm your schema prefix. This follows a pattern [pub_username_substack_com] or [pub_customdomain_com] based on what publications you have configured in StackContacts tool.

Quick check:

Show me the table names for subscribers_detail, subscriber_events, and gumroad_sales in the StackContacts tool.

2. Customize the Prompt (Optional)

Adjustments based on your business:

• Date range: Add WHERE created_at >= '2024-XX-XX' to focus on recent data

• Engagement thresholds: Adjust “50+ events” to match your posting frequency

• LTV tiers: Change dollar amounts ($100, $50, $20) to fit your product pricing

• Product limits: Increase/decrease “top 30” in Analysis #5 based on your product count

3. Execute the Prompt

1. Open Cursor IDE with Claude, or Claude Desktop with configured StackContacts MCP server.

2. Paste the full prompt

3. Wait 60-90 seconds (runs at least 7 cross-platform queries)

4. Claude returns 7 analyses showing unified customer view

4. Verify the Results

What you should see:

• Analysis 1: Overlap showing 15-25% of customers are also subscribers (typical range)

• Analysis 2: 70-85% “Gumroad Only” customers (most creators have this blind spot)

• Analysis 3: Power customers with 3-5x higher LTV than one-time buyers

• Analysis 4: Highly engaged customers spending 50-100% more than non-engaged

• Analysis 5: Specific posts linked to specific products (content affinity)

• Analysis 6: 30-50% of direct sales coming from Substack links (even for non-subscribers)

• Analysis 7: VIP customers engaging with 15-25 posts on average

Red flags to watch for:

• Overlap > 50%: Most customers are subscribers—you’re not reaching new audiences

• Overlap < 10%: Very few customers subscribe—your content isn’t converting readers

• All customers in “No Engagement”: Email matching might be failing—check data quality

• Zero content affinity: Products might not be mentioned in posts—add more CTAs

Troubleshooting:

• If Analysis #1 shows 0 matched emails: Check email formatting (lowercase, trim spaces)

• If Analysis #5 returns empty: Customers might not have pre-purchase engagement—extend window to 60 or 90 days

• If Analysis #6 shows “NULL” for referrers: Gumroad might not be tracking referrers—check your Gumroad settings

Understanding Your Results: How to Interpret the Data

What the Numbers Mean

Analysis 1: Email Matching & Overlap

Substack Emails:1,175 
Gumroad Emails: 919 
Matched:183
% Customers Are Subscribers: 19.91% 
% Subscribers Are Customers: 15.57%

Interpretation:

• 1,175 Substack subscribers (your content audience)

• 919 Gumroad customers (your product buyers)

• 183 matched emails (people in both systems using same email address)

• 19.91% of customers are subscribers - 4 out of 5 buyers never signed up for your newsletter (or used different email for Gumroad)

• 15.57% of subscribers are customers - Only 1 in 6 subscribers has bought

Key insight: You have 736 “dark customers” (80%) who bought without subscribing. These are high-intent buyers you can’t nurture, can’t upsell to, and can’t engage with through email campaigns. Massive untapped opportunity.

Analysis 2: Customer Segmentation by Engagement

| Data Completeness | Customers | % of Customers | Avg Spend | Avg Posts Engaged |
|-------------------|-----------|----------------|-----------|-------------------|
| Gumroad Only      | 736       | 80.09%         | $14.70    | 0.0               |
| Full Data         | 183       | 19.91%         | $19.60    | 17.55             |

Interpretation:

• 80.09% of customers have zero Substack data (can’t track their journey)

• 19.91% of customers have full data (subscriber profile + engagement history)

• Full-data customers spend 33% more ($19.60 vs. $14.70)

• Full-data customers engage with 17.55 posts on average (high investment in your content)

Key insight: Converting “Gumroad Only” customers to engaged subscribers could boost average LTV from $14.70 to $19.60 - this is a 33% increase.

At 736 customers, that’s $3,606 in additional revenue just from better cross-platform integration.

Analysis 3: Customer Lifetime Value (LTV) by Purchase Behavior

| Customer Segment          | Count | Avg Purchases | Avg LTV | Avg Lifespan (Days) |
|---------------------------|-------|---------------|---------|---------------------|
| Power Customer (4+)       | 25    | 5.04          | $54.40  | 190.11              |
| Multi-Product (2-3)       | 212   | 2.33          | $39.12  | 100.01              |
| One-Time Buyer            | 662   | 1.00          | $16.32  | 0.00                |
| Repeat Single Product     | 20    | 2.40          | $11.50  | 66.03               |

Interpretation:

• Power Customers (25): Buy 4+ products, spend $54.40, stay active for 190 days (6+ months)

• Multi-Product (212): Buy 2-3 products, spend $39.12, active for 100 days

• One-Time Buyers (662): 72% of customers buy once and never return, spend $16.32

• Repeat Single Product (20): Buy same product multiple times (subscriptions?), lowest LTV

Key insight: Your top 25 customers (2.7% of buyers) spend 3.3x more than average. And 212 multi-product buyers (23%) drive significantly higher LTV. Focus on moving one-time buyers into the multi-product segment.

Analysis 4: Engagement-LTV Correlation

| Engagement Level   | Customers | Avg Purchases | Avg Products | Avg LTV | Avg Posts |
|--------------------|-----------|---------------|--------------|---------|-----------|
| Moderately Engaged | 39        | 1.59          | 1.56         | $40.35  | 3.0       |
| Highly Engaged     | 137       | 2.03          | 1.82         | $36.29  | 20.2      |
| Lightly Engaged    | 7         | 1.57          | 1.57         | $22.97  | 0.29      |
| No Engagement      | 736       | 1.33          | 1.28         | $19.00  | 0.0       |

Interpretation:

• Moderately Engaged (39 customers, 3 posts): Highest LTV at $40.35 (2.1x higher than non-engaged)

• Highly Engaged (137 customers, 20.2 posts): $36.29 LTV, 2.03 purchases (most loyal)

• No Engagement (736): $19.00 LTV, 1.33 purchases (80% of customers)

Why is “Moderately Engaged” highest LTV? Sweet spot—they engage enough to build trust (3 posts) but aren’t “browsers” who read everything. They’re problem-solvers who read your content, find solutions, and buy.

Key insight: Engagement drives spending, but there’s a quality threshold. Getting customers to read 3-5 targeted posts is more valuable than getting them to read 20 random posts. Focus on converting the 736 non-engaged customers to “moderately engaged” status.

Analysis 5: Content-to-Product Affinity

| Product Name               | Post Title           | Buyers Who Read | Engagements|
|----------------------------|----------------------|-----------------|-------------|
| Finn Tropy Substack Pro Studio| Substack Pro Studio User Guide | 32   | 585         |
| Finn Tropy Substack Pro Studio| How To Write Notes That Convert| 19   | 253         |
| Finn Tropy Substack Pro Studio 🔥 Growth Test for Serious ...  | 19   | 285         |
| Substack Control Center | You're Publishing Weekly, But ...    | 11   | 166         |
| Substack Control Center | How I Turned My Substack Posts ...   | 9    | 99          |
| CreativeTech Pro Studio (Bundle)| Substack Pro Studio User ... | 12   | 63          |

Interpretation:

• “Substack Pro Studio User Guide” is the #1 gateway content for your Pro Studio product (32 buyers read it before purchasing)

• “How To Write Notes That Convert” drives 19 Pro Studio sales (253 engagements)

• Different posts lead to different products (Control Center buyers read different content than Pro Studio buyers)

Key insight: Each product has “gateway content”—specific posts that prime buyers. Double down on these posts:

• Reference them in product descriptions

• Link to them in follow-up emails

• Repost them as Notes

• Turn them into lead magnets

Analysis 6: Channel Attribution for Direct Customers

| Traffic Source             | Sales | Customers | % of Direct Sales |
|----------------------------|-------|-----------|-------------------|
| Other Referrer             | 324   | 278       | 33.13%            |
| Substack (Post/Note Link)  | 304   | 277       | 31.08%            |
| Direct/Unknown             | 243   | 210       | 24.85%            |
| Google Search              | 78    | 77        | 7.98%             |
| Twitter                    | 15    | 15        | 1.53%             |
| Gumroad Library            | 14    | 10        | 1.43%             |

Interpretation:

• 31.08% of non-subscribers still come from Substack links (they clicked but didn’t subscribe)

• 33.13% come from “Other Referrer” (likely other blogs, forums, YouTube, podcasts)

• 7.98% from Google Search (SEO working, but not a huge driver)

• 1.53% from Twitter (low—opportunity to grow here?)

Key insight: Substack content drives 31% of direct sales even when people don’t subscribe. Your posts are working as product landing pages. But you’re not capturing these leads—304 buyers clicked through without subscribing.

Add subscription CTAs to your product-focused posts.

Analysis 7: Top Customer Engagement Analysis

| Customer Tier| Customers| Avg Spent| Avg Purchases| Avg Posts| Avg Events|Avg Clicks|
|--------------|----------|----------|--------------|----------|-----------|----------|
| VIP ($100+)  | 14       | $120.43  | 4.14         | 16.29    | 169.0     | 3.71     |
| High Value   | 36       | $89.06   | 1.75         | 4.25     | 60.06     | 1.44     |

Interpretation:

• 14 VIP customers spend $120+ each, averaging 4.14 purchases and engaging with 16.29 posts

• 36 high-value customers spend $50-99, with lower engagement (4.25 posts)

Key insight: Your VIPs are deeply engaged (169 events, 16 posts). They’re not casual buyers - they’re superfans who read your content regularly and buy multiple products. Identify them by name and give them white-glove treatment:

• Personal thank-you emails

• Early access to new products

• Direct line to you for support

• Exclusive content or community access

Pattern Recognition

Pattern 1: The 80/20 Dark Customer Problem

80% of your customers have zero Substack engagement. They found your product, bought it, and disappeared.

Why? They discovered your content through search or referrals, clicked your product link, and bought without ever subscribing. Or they bought from a repost/share without visiting your Substack.

Action: Add a post-purchase email sequence:

1. “Thanks for buying [product]! Want to get more value? Subscribe to my newsletter for advanced tips.”

2. Include link to best posts related to the product they bought

3. Offer a content upgrade (guide, template, case study) in exchange for subscribing

Pattern 2: Engagement = 2x LTV (But Only to a Point)

Moderately engaged customers ($40.35 LTV) spend more than highly engaged ($36.29) and WAY more than non-engaged ($19.00).

Why? Reading 3-5 posts builds trust and demonstrates value without turning readers into “browsers.” Highly engaged readers might enjoy your writing but not need your products (yet).

Action: Don’t optimize for maximum engagement. Optimize for relevant engagement—get customers to read the 3-5 posts that best showcase your products.

Pattern 3: Gateway Content Exists for Every Product

Specific posts consistently appear before specific product purchases. “User Guides” dominate, but tactical “how-to” posts also drive sales.

Why? Buyers want proof of value before purchasing. Reading a user guide shows them exactly what they’ll get. How-to posts demonstrate your expertise.

Action: For every product:

1. Write a detailed user guide (even before launch)

2. Create 2-3 tactical how-to posts showing the product in action

3. Link these posts in your product description

4. Reference them in sales emails

Pattern 4: Substack Links Drive 31% of “Non-Subscriber” Sales

Nearly 1 in 3 direct customers found your product through a Substack link but didn’t subscribe.

Why? They were in “problem-solving mode”—clicked for the solution, bought immediately, and left. They weren’t thinking about long-term content consumption.

Action: Add inline subscription CTAs to product-focused posts:

• “Want more insights like this? Subscribe below.”

• “I share weekly tips on [topic]—join 1,000+ creators.”

• Pop-up on exit intent: “Before you go, grab my free [resource]”

Red Flags to Watch For

Warning Sign 1: Overlap < 10%

If fewer than 10% of customers are subscribers, your Substack content isn’t converting readers to buyers. You have an audience but no sales funnel.

Action: Audit your posts—how many mention your products? Add more product references, CTAs, and use cases. Make buying a natural next step.

Warning Sign 2: VIP Customers with Low Engagement

If your highest spenders barely engage with content, they’re discovering products elsewhere (referrals, search, ads). Your content isn’t driving revenue.

Action: Survey VIP customers: “How did you find us?” Double down on whatever channel they mention.

Warning Sign 3: All Customers Are One-Time Buyers

If you have no multi-product or power customers, your products don’t complement each other or you’re not cross-selling.

Action: Create product bundles, build upgrade paths (Basic → Pro), and send post-purchase upsell emails.

Actionable Insights

How to translate numbers into decisions:

Insight: “80% of customers have no Substack data”
Action: Launch post-purchase nurture sequence:

• Email 1: “Get more value from [product] with these posts...”

• Email 2: “Advanced tips every week—subscribe here”

• Track conversion rate (how many direct customers become subscribers)

Insight: “Moderately engaged customers spend $40.35 vs. $19.00 for non-engaged (2.1x)”
Action: Create a “New Customer Onboarding” sequence:

• Send 3-5 best posts related to their purchase

• Include product tips, case studies, and tutorials

• Goal: Move them from “no engagement” to “moderately engaged” (3-5 posts)

Insight: “Power customers buy 4+ products and spend $54.40 (3.3x average)”
Action: Identify your 25 power customers by name:

• Send personal thank-you email

• Offer exclusive early access to new products

• Ask for feedback on product roadmap

• Create a private Slack/Discord for VIPs

Insight: “Substack links drive 31% of non-subscriber sales”
Action: Add subscription CTAs to all product-focused posts:

• Inline: “Subscribe for more insights like this”

• Exit pop-up: “Before you go, grab my free template”

• Post-click: “You clicked [product link]—want weekly updates?”

Insight: “’User Guide’ posts are gateway content for multiple products”
Action: Write user guides for EVERY product:

• Publish them on Substack (not just in product docs)

• Link from product description: “Read the full guide here”

• Reference in sales emails: “See it in action”

Prioritization Framework

Priority 1: Convert Dark Customers to Subscribers

Impact: 736 customers with zero engagement—converting 20% would add 147 engaged subscribers

Actions:

1. Export list of Gumroad customers not in subscribers_detail

2. Send post-purchase email sequence:

   • “Thanks for [product]! Here are 3 posts to get more value...”

   • Include subscribe CTA

   • Offer content upgrade (template, guide) in exchange for subscribing

3. Track conversion rate weekly

4. Test subject lines, offers, and timing

Expected impact: 15-25% of direct customers subscribe, boosting future upsell opportunities

Priority 2: Create Gateway Content for Each Product

Impact: Drive more sales from existing audience by showing value upfront

Actions:

1. For each product, write:

   • Detailed user guide (400-800 words)

   • How-to tutorial showing product in action

   • Case study or before/after results

2. Publish on Substack (make public or free)

3. Link from product description: “Read the guide”

4. Reference in sales emails

5. Track views → clicks → purchases for each post

Expected impact: 20-30% increase in product page conversion rate

Priority 3: Build Power Customer Retention Program

Impact: 25 power customers at $54 LTV—losing even 5 would cost $270 in future revenue

Actions:

1. Export list of customers with 4+ product purchases

2. Send personal email: “You’re a VIP customer—want early access to [new product]?”

3. Create exclusive channel (private DMs, email list, Discord, Slack, etc)

4. Offer special perks:

   • 30% discount on future products

   • Free upgrades when you launch new versions

   • Direct priority support

5. Survey them quarterly: “What should we build next?”

Expected impact: 80-90% retention rate for power customers (vs. 50% without program)

Priority 4: Optimize Substack-to-Gumroad Conversion Flow

Impact: 31% of non-subscribers come from Substack links—improving that flow boosts sales 10-20%

Actions:

1. Audit product-focused posts—how prominent are CTAs?

2. Add multiple CTAs:

   • Inline (middle of post)

   • End of post

   • PS section

3. A/B test CTA copy:

   • “Check out [product]” vs. “Get [product] (20% off today)”

   • “Learn more” vs. “Buy now”

4. Add exit-intent pop-up on product-focused posts

5. Track: Post views → link clicks → purchases

Expected impact: 15-25% increase in Substack → Gumroad conversion rate

Case Study: Real Results from My Data

The Setup

• Publication: Finn’sights (finntropy.substack.com)

• Substack Subscribers: 1,175

• Gumroad Customers: 919

• Time Period: August 2024 - December 2025 (16 months)

• Products: 10 Substack creator tools ($0-$79)

• Hypothesis: “Unifying Substack + Gumroad data will reveal hidden revenue opportunities”

The Analysis

I ran the cross-platform insights prompt on my StackContacts database. What I discovered completely changed my product strategy.

Key Findings:

1. 80.09% of customers (736) never subscribed to my Substack (or used different email address)

2. Full-data customers spend 33% more ($19.60 vs. $14.70)

3. Power customers (25) spend 3.3x more than average ($54.40 vs. $16.50)

4. Moderately engaged customers have highest LTV ($40.35 for 3 posts vs. $19 for 0 posts)

5. “User Guide” posts are gateway content for multiple products

6. 31% of non-subscribers found products through Substack links

Surprising Findings

Surprise #1: 80% of my customers are invisible

I assumed most customers came from my newsletter.
Nope. 736 out of 919 customers (80%) bought without subscribing.

They found my products through:

• Substack post links (31%) - clicked through without subscribing

• Google search (8%) - landed on product-focused posts

• Referrals (33%) - shared by others

• Twitter (1.5%) - tiny but present

Why this shocked me: I was spending 80% of my time creating content for subscribers, but 80% of revenue came from non-subscribers.

Result: I started treating every product-focused post as a landing page with clear subscribe CTAs.

Outcome: Conversion rate of direct customers → subscribers jumped from 5% to 18% (+260% improvement).

Surprise #2: Moderate engagement = highest LTV

I expected highly engaged readers (20+ posts) to be my best customers. Wrong.

• Moderately engaged (3 posts): $40.35 LTV

• Highly engaged (20 posts): $36.29 LTV

• No engagement: $19.00 LTV

Why? Moderately engaged customers read just enough to build trust and see value. They’re not “browsers”—they’re problem-solvers who read targeted content and buy solutions.

Highly engaged readers enjoy my writing but might not have urgent problems my products solve (yet).

Result: I stopped optimizing for maximum engagement and started creating “onboarding sequences” focused on 3-5 key posts.

Outcome: New customer 30-day LTV increased from $16.50 to $24.20 (+47% improvement).

Surprise #3: I have 25 power customers worth $1,360

Before this analysis, I treated all customers the same. But 25 customers bought 4+ products, spending $54.40 each ($1,360 total).

These weren’t random buyers—they were superfans who:

• Engaged with 16+ posts on average

• Bought multiple products over 6+ months

• Actively clicked links (3.71 clicks per customer)

Why I missed them: They were buried in a list of 919 customers. No way to identify them without cross-platform analysis.

Result: I manually reached out to all 25:

• Personal thank-you email or DMs

• Offered discounts on new products

• Invited to private beta testing with early access to new products

• Asked for product roadmap feedback and features they need

Outcome: 23 replied (92% response rate), 18 bought my next product launch within 48 hours, and 3 became beta testers.

Surprise #4: “User Guide” posts drive sales across multiple products

I thought each product needed unique content. But “Substack Pro Studio User Guide” appeared in the pre-purchase engagement for:

• Finn Tropy Substack Pro Studio (32 buyers)

• CreativeTech Bundle (12 buyers)

• Substack Control Center (8 buyers)

Why? User guides demonstrate value and reduce purchase friction. Buyers want to see exactly what they’re getting before clicking “Buy.”

Result: I wrote detailed user guides for every product and published them as Substack posts (not just in product docs).

Outcome: Product page conversion rate increased from 12% to 19% (+58% improvement).

The Impact

What I changed based on cross-platform insights:

1. Launched post-purchase email sequence - Convert direct customers to subscribers

2. Created onboarding emails - Move new customers to “moderately engaged” status

3. Built VIP customer program - 25 power customers get white-glove treatment

4. Wrote user guides for all products - Published on Substack as gateway content

5. Added subscribe CTAs to product posts - Capture leads who click Gumroad links

Measurable outcomes:

• Direct customer → subscriber conversion: 5% → 18% (+260% improvement)

• New customer 30-day LTV: $16.50 → $24.20 (+47% improvement)

• Power customer retention: 92% response rate to VIP outreach

• Product page conversion rate: 12% → 19% (+58% improvement)

• Total additional revenue (6 months): ~$4,800 from better cross-platform integration

Key Takeaway

The one insight that mattered most:

You don’t have two audiences—you have ONE audience experiencing your business across two platforms.
Treating them as separate leaves massive revenue on the table.

Before cross-platform analysis, I saw:

• Substack: “I have 1,175 subscribers”

• Gumroad: “I have 919 customers”

Now I see:

• 183 subscriber-customers (engaged + buying) - nurture heavily

• 992 subscribers who haven’t bought (warm leads) - targeted sales campaigns

• 736 customers who aren’t subscribers (dark customers) - convert to engaged subscribers

• 25 power customers (superfans) - VIP treatment

Each segment needs a different strategy. And I only discovered them by unifying the data.

Why this analysis was worth doing:

Cross-platform insights revealed $4,800 in quick-win revenue opportunities I couldn’t see before:

• Converting 20% of dark customers to subscribers (future upsell opportunity)

• Boosting LTV 47% by onboarding customers to moderate engagement

• Retaining 25 power customers worth $1,360 in repeat purchases

• Improving product conversion 58% with better gateway content

That’s the difference between managing two silos and running one integrated business.

Advanced Applications: Taking It Further

Variations on the Prompt

Variation 1: Product Purchase Sequences

Identify common product purchase paths:

For customers who bought multiple products, calculate:
- Which product was purchased first, second, third, etc.
- Time between purchases
- Most common product sequences (e.g., Product A → Product B → Product C)

Create a product flow diagram showing typical upgrade paths.

Insight: Optimize product bundles and upsell sequences based on natural purchase progressions.

Variation 2: Churn Risk Scoring

Identify customers likely to disengage:

For subscriber-customers, calculate:
- Days since last purchase
- Days since last Substack engagement
- Drop in engagement velocity (month-over-month)

Flag customers showing "cooling" patterns (high engagement → low engagement).

Insight: Run re-engagement campaigns before customers churn completely.

Variation 3: Lookalike Audience Building

Profile your best customers to find similar prospects:

For power customers (4+ products), analyze:
- Which Substack posts they engage with most
- Their engagement patterns (frequency, timing, content types)
- Product categories they prefer

Find current subscribers who match these patterns but haven't bought yet.

Insight: Target “lookalike” subscribers with personalized product recommendations.

Integration Opportunities

Combine Cross-Platform with Other StackContacts Analyses:

1. Cross-Platform + Revenue Attribution

See which content drives specific customer segments:

For each customer segment (power, multi-product, one-time):
- Which posts do they engage with before buying?
- Which posts have highest conversion rate for each segment?
- Which content types (tutorials, case studies, user guides) work best?

Create segment-specific content strategies.

Outcome: Write content tailored to each customer tier’s preferences.

2. Cross-Platform + Predictive Analytics

Build purchase propensity models across platforms:

For subscribers who haven't bought yet:
- Calculate their "customer similarity score" (how closely they match existing buyer behavior)
- Identify high-propensity prospects (match power customer patterns)
- Flag subscribers entering "purchase window" (engagement spike + link clicks)

Create tiered prospect lists: Hot, Warm, Cold based on cross-platform signals.

Outcome: Prioritize sales outreach to subscribers most likely to buy.

3. Cross-Platform + Engagement Velocity

Track how Substack engagement impacts Gumroad purchasing timing:

For subscriber-customers, analyze:
- Engagement velocity in the 7 days before purchase
- Which engagement spike patterns predict buying
- Optimal time to send product offers (after X posts read, Y links clicked)

Build automated triggers: "If subscriber reads 3 posts + clicks 1 link in 7 days → send product offer email."

Outcome: Perfectly timed sales outreach based on cross-platform momentum.

Next-Level Questions

Questions to explore after building your unified view:

1. “Which products have the highest subscriber → customer conversion rate?”

   • Compare conversion rates across your product line

   • Double down on products that convert subscribers best

2. “Do power customers discover me differently than one-time buyers?”

   • Segment referrer data by customer tier

   • Invest in channels that attract high-LTV customers

3. “What’s the ROI of converting a direct customer to a subscriber?”

   • Calculate: (Subscriber-Customer LTV - Direct Customer LTV) × Conversion Rate

   • Justify investment in post-purchase nurture campaigns

4. “Which subscriber content consumption patterns predict multi-product purchases?”

   • Find common post reading sequences before power customer conversions

   • Build content funnels that replicate those patterns

5. “How does cross-platform engagement correlate with customer lifetime?”

   • Compare lifespan (first → last purchase) for engaged vs. non-engaged customers

   • Prove engagement drives retention, not just initial sales

Common Pitfalls and How to Avoid Them

Data Quality Issues

Problem 1: Email Formatting Inconsistencies

Emails might have different formats across platforms (uppercase vs. lowercase, trailing spaces, plus-addressing like user+tag@email.com).

How to spot it:

• Overlap percentage is unexpectedly low (<10%)

• Manual checking reveals customers you know are subscribers but don’t match

How to fix it:

-- Normalize emails before matching
SELECT LOWER(TRIM(email)) as email_normalized
FROM subscribers_detail

Problem 2: Missing Referrer Data

Gumroad doesn’t always capture referrer information, especially for mobile purchases or certain browsers.

How to spot it:

• Large percentage of “Direct/Unknown” traffic (>50%)

• Analysis #6 shows NULL for most referrers

How to fix it:

• Use UTM parameters in all Gumroad links: ?utm_source=substack&utm_campaign=post123

• Track UTM parameters separately in your own database

• Survey customers: “How did you hear about us?”

Problem 3: Duplicate Customers

Some customers might use multiple email addresses across platforms.

How to spot it:

• Customer count seems inflated

• Same name appears with different emails in Gumroad

How to fix it:

• Manually deduplicate VIP/power customers by name

• Use fuzzy matching on names + email addresses (advanced)

• Accept some duplication—perfect matching is impossible

Misinterpretation Risks

Risk 1: Confusing Correlation with Causation

Just because subscriber-customers spend more doesn’t mean subscribing CAUSES higher spending. Maybe high-intent buyers naturally engage more.

How to avoid it:

• Run A/B test: Send post-purchase nurture emails to 50% of direct customers, track LTV difference

• Compare before/after LTV for customers who subscribed post-purchase vs. those who didn’t

• Look for directional evidence, not absolute proof

Risk 2: Over-Optimizing for Power Customers

Focusing only on your top 25 customers might neglect the 662 one-time buyers who could become repeat customers.

How to avoid it:

• Balance attention: 40% power customers, 40% multi-product buyers, 20% one-time buyers

• Test activation campaigns for one-time buyers: “Buy a second product and get 20% off”

• Track segment transitions (how many one-time → multi-product?)

Risk 3: Assuming All Non-Subscribers Need to Subscribe

Some customers prefer transactional relationships—they want products, not newsletters.

How to avoid it:

• Respect preferences: Add “product updates only” email option

• Track unsubscribe rates for post-purchase nurture campaigns

• A/B test value prop: “Weekly tips” vs. “Product updates + tips”

Best Practices

How often to run this analysis:

• Monthly: Full cross-platform refresh to track segment changes

• After product launches: See how new products affect customer segmentation

• Quarterly: Deep dive into power customer behavior, update VIP program

• Annually: Strategic review of platform overlap, channel attribution, LTV trends

When to update your approach:

• New product line: Different products might attract different customer types

• Pricing changes: LTV thresholds might need adjustment

• Audience growth: As you scale past 5K subscribers, patterns might shift

• Platform changes: If Substack or Gumroad add new features, update queries

How to track changes over time:

• Export key metrics monthly to spreadsheet:

  • Platform overlap percentage

  • % customers with full data

  • Average LTV by engagement level

  • Power customer count

  • Top gateway content (changes over time?)

• Set alerts: If overlap drops below 15% or power customers churn, investigate immediately

Your Turn: Try It and Share

Call to Action

Ready to unify YOUR Substack and Gumroad data?

1. Copy the AI prompt from this article

2. Paste into Claude (connected to StackContacts)

3. Run the 7 analyses and review your cross-platform insights

4. Identify your dark customers and power customers

5. Reply with your findings: What % of YOUR customers have no Substack data?

Questions to explore:

• How many “dark customers” do you have?

• What’s YOUR overlap percentage? (Higher or lower than 19.91%?)

• Do engaged customers spend more for you too?

Community Engagement

Share your surprising cross-platform insights:

• “85% of my customers never subscribed—totally blind to them!”

• “Our power customers spend $200+ each—building a VIP program now”

• “Discovered that ‘How-To’ posts drive 3x more sales than case studies”

Compare across niches:

• B2B creators likely have higher overlap (subscribers become customers)

• Tool/product creators might have more direct customers (Google search traffic)

• Coaches/consultants might have deeper engagement before purchasing

Your data will differ. That’s the point—unify YOUR platforms and optimize for YOUR patterns.

Office Hours Invitation

Want help analyzing your cross-platform data?

Bring your unified customer view to weekly office hours (paid subscribers only):

• Review your platform overlap and dark customer strategy

• Discuss power customer retention programs

• Get feedback on post-purchase nurture campaigns

• Ask about advanced cross-platform scoring models

Next office hours: February 4th, 2026 at 1 PM EST - send a DM to get an invitation.

Key Takeaways

✅ 80% of Gumroad customers never subscribe to Substack—you’re blind to most of your buyers

✅ Subscriber-customers spend 33% more than direct customers ($19.60 vs. $14.70)

✅ Power customers (4+ products) spend 3.3x more than one-time buyers ($54.40 vs. $16.32)

✅ Moderately engaged customers have highest LTV—3-5 posts is the sweet spot for conversion

✅ “User Guide” posts are gateway content—they drive purchases across multiple products

✅ 31% of non-subscribers find products through Substack links—add subscribe CTAs to capture them

✅ VIP customers (top 50 by spend) engage with 16+ posts—identify and nurture them personally

✅ Run monthly cross-platform analysis to track segment changes and optimize strategies

— Finn

I study creator growth the way engineers study systems—with experiments, dashboards, and curiosity. I built StackContacts to turn subscriber data into revenue, and I share weekly AI prompts, research, and office hours to help you extract maximum value from your investment.

Get StackContacts: https://www.stackcontacts.com/

About This Article:

• Data Source: FinnTropy StackContacts database (Aug 2024 - Dec 2025)

• Analysis Method: Cross-platform email matching, cohort comparison, LTV calculation

• Platforms Unified: Substack (1,175 subscribers) + Gumroad (919 customers)

• Key Finding: 80% of customers have no Substack engagement data (736 “dark customers”)