Plunk

Plunk is an open-source email platform that combines transactional email delivery, marketing campaigns, and workflow automation in a single service. It handles everything from password reset emails to complex marketing sequences, offering a complete email infrastructure solution. The platform charges $0.001 per email with no contact limits, making it cost-effective for growing businesses.

The platform stands out with its visual workflow builder that requires no coding, allowing users to create email sequences with triggers, delays, and conditional logic. It provides real-time audience segmentation based on contact behavior and detailed analytics across all email types. Plunk is AGPL-3.0 licensed, EU-hosted, GDPR compliant, and can be self-hosted on any infrastructure using Docker Compose.

Plunk works best for developers and startups who need a transparent, scalable email solution without vendor lock-in. Typical use cases include sending transactional emails for applications, running marketing campaigns, and creating automated onboarding sequences. The platform's unified contact history tracks all interactions across transactional, campaign, and workflow emails in one place.