Email marketing as code (open source Customer.io alternative)

After getting frustrated with Customer.io's limitations, I built an open-source alternative that lets you write marketing automation in pure code. Define user segments in SQL, write email flows in TypeScript, and template emails in React+Tailwind. Support for campaigns, segments, events, users, and transactions. SMS support planned.

Visit segflow.io ↗Alternatives

Does the same job

all alternatives →

UnosendDec 2025 · ▲205
Send transactional + marketing email w/ 99.9% deliverability
React Email 6.0Apr 2026 · ▲91
An open-source email editor you can embed in your own app
Codemail.io2025 · ▲88
Send emails with perfectly formatted code snippets
React Email 6.0 by ResendApr 2026 · ▲135
Build, customize, and ship emails — all from your own app
Great Email Templates2021 · ▲127
HubSpot email templates for SaaS marketers
[Sending]flow2024 · ▲191
All-in-one Webflow email autoresponder

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