Product Market Fit
Investor Due Diligence Report
by Guillermo Flor
substackBusiness
Daily high-signal content on how to build, grow and fund startups in the AI era.
Investor Due Diligence Report
by Guillermo Flor
Daily high-signal content on how to build, grow and fund startups in the AI era.
76K
2.2K paid
+1.5%
+4.1%
net growth
Pricing
$99.99/mo
$299/yr annual option
$92K
2.2K paid subs
$92K/mo – $92K/mo(±0%)
0.1
53.3
0.07%
(comments + likes) / subscribers
~3x per week
3.5 posts/week
69/100
Consistent (~2.1d avg)
| Newsletter | Subscribers | Weekly Growth | Price | Platform |
|---|---|---|---|---|
| Ravi on Product | 32K | N/A | Free | substack |
| GTM Vault | 26K | N/A | $10/mo | substack |
| Joe Reis | 15K | N/A | Free | substack |
| Attorney Bobbie Anne Cox... Knowledge is power! | 11K | N/A | $7/mo | substack |
| Month | Subscribers | Est. Revenue | Change |
|---|---|---|---|
| Feb 2026 | 66.5K | $80,906.65 | — |
| Mar 2026 | 69.5K | $84,578.4 | +4.5% |
| Apr 2026 | 72K | $87,609.73 | +3.6% |
| May 2026 | 73K | $88,847.88 | ~0% |
| Jun 2026 | 75K | $91,281.48 | +2.7% |
Platform Dependency
Operates on custom domain (www.productmarketfit.tech)
Publishing Consistency
Variable publishing frequency
Key Person
Single-author publication — key-person dependency
Audience Concentration
Consistent engagement across posts
Subscriber threshold
76K subscribers — above the 2K category median for first paid tier
Has paid tier
Active paid subscription offering
Peer monetization
100% of 63 similar-size peers in Business have paid tiers
Pricing position
$99.99/mo vs $7/mo category median (1493 newsletters)
| Date | Monthly | Annual |
|---|---|---|
| Apr 2026 | $100 | $299 |
| Jan 2026 | $60 | $240 |
Disclaimer: This report is generated automatically based on publicly available data and proprietary estimation models. Estimated subscriber counts are derived from engagement patterns and should be verified through direct disclosure. Revenue estimates are based on known pricing and estimated paid subscriber counts. This report is for informational purposes only and should not be the sole basis for investment decisions.
| Component | Score | Weight |
|---|---|---|
| Engagement Rate | 46/100 | 30% |
| Paid Subscriber Ratio | 47/100 | 25% |
| Growth Consistency | 86/100 | 15% |
| Publishing Consistency | 86/100 | 10% |
| luttig's learnings |
| 10K |
| N/A |
| Free |
| substack |
Revenue Model
Active paid subscription tier