Build a Gumroad Lead Machine in Google Sheets (Ping Webhook + License API + AI Upsell)

Short summary

The post describes a low-friction B2B lead-gen system: sell a $29 product on Gumroad, capture each sale via a ping webhook into Google Sheets using Apps Script, verify the license against Gumroad's API, and send an AI-personalized upsell email via GPT-4o-mini. The approach replaces traditional form-based funnels with a paid micro-commitment that qualifies leads by wallet intent. Full Apps Script code is provided for webhook handling, deduplication, license verification, and automated email follow-up.

• •Sell a small paid product on Gumroad to qualify leads instead of using low-converting demo forms
• •Apps Script webhook logs sales into Google Sheets, dedupes by sale_id, and verifies licenses via Gumroad API
• •GPT-4o-mini generates personalized upsell emails at under $0.01 each, with template fallback

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