From open-source donations to $13k MRR product

TL;DR: Andris Reinman created Nodemailer, an open-source email library used by hundreds of thousands of developers, but donations only brought low hundreds per month. After years of burnout as a startup CTO, he wanted a calmer business. He tried multiple monetization approaches for EmailEngine: first as an open-source project hoping for increased donations, then dual-licensing (AGPL free / MIT paid) for 1.5 years with almost no takers. Only when going fully commercial with mandatory subscriptions did customers immediately start paying. His distribution strategy is entirely engineering-led with $0 marketing budget. He releases multiple free/open-source email tools that link to EmailEngine. Users of Nodemailer who need features it does not provide (like Microsoft Graph API) naturally discover EmailEngine. He also writes EmailEngine vs. competitor SEO articles to capture users actively looking for alternatives. Critically, he designed the business for lifestyle over maximum growth: self-serve customers only, no enterprise sales demos, no managed hosting. He refers customers asking for demos to competitors. This keeps support burden low with competent technical teams who require minimal hand-holding. The business grew slowly but steadily from $500 MRR when he went full-time to $13k MRR at roughly 20% yearly growth - no sudden bumps, just linear progression. As a solo business with minimal costs based in Eastern Europe, he has no plans to push for faster growth.