Plunk alternatives in Transactional Email & Developer Email APIs

Plunk positions itself as the affordable, open-source, self-hostable alternative to commercial transactional and marketing email platforms such as SendGrid, Resend, and Mailgun. Its primary differentiators are: per-email pricing at $0.001 (undercutting most rivals), unlimited contact storage at no extra cost, AGPL-3.0 open-source licensing, and a sub-5-minute setup promise. Unlike enterprise-focused platforms, Plunk explicitly targets indie hackers, solopreneurs, and small SaaS teams who need both transactional and marketing email in a single, developer-first tool without feature gating or contact-based pricing tiers.