The best open-source Marketing Automation tools, curated: 6 in the registry, including Claude Ads (independent — AI agent for auditing ads across 12 platforms), Billion Mail, Dittofeed. Every tool is open-source; each entry lists license, self-hostability, and links.
Claude Ads (independent — AI agent for auditing ads across 12 platforms)· tool, 2026-10-19 MIT-licensed, self-hostable Claude Code skill / Python package that lets an AI agent audit and draft optimizations for ad accounts across 12 platforms (Google, Meta, YouTube, LinkedIn, TikTok and more), read-only by default with account changes gated behind explicit approval and rollback, so a lean team can run paid-ads review on tooling it owns instead of a managed ad-ops service.
Billion Mail· tool, 2026-09-13 Fully self-hosted, open-source (AGPL-3.0) email server and email-marketing platform: newsletters, campaigns and transactional mail on your own server, free of monthly per-subscriber fees. Vendor claims an 8-minute install to first sent email. An open alternative to Mailchimp (~15.6k stars).
Dittofeed· tool, 2026-09-03 OSS alt to Customer.io; ~2888 stars; via openalternative.co
Plunk· tool, 2026-09-03 OSS alt to Resend; ~5347 stars; via openalternative.co
Sendune· tool, 2026-09-03 OSS alt to Resend; ~2182 stars; via openalternative.co
useSend· tool, 2026-09-03 OSS alt to Resend; ~4586 stars; via openalternative.co