BillionMail vs Klaviyo
BillionMail and Klaviyo are both email marketing software. BillionMail is open source under AGPL-3.0, with 16k GitHub stars. Klaviyo is a commercial product from Klaviyo.
Which to pick
- Pick BillionMail when
- You want to run your own mail server and campaigns together and know how to manage IP reputation.
- Pick Klaviyo when
- A Shopify or other online store wants purchase-driven email and SMS marketing.
Side by side
Bundles a mail server (Postfix, Dovecot, Rspamd) with newsletter and email marketing tools in one self-hosted package.
Email and SMS marketing for e-commerce, using store purchase data for segmentation, flows like abandoned cart, and revenue attribution.
Running your own outbound mail server is hard to get delivered; activity slowed after June 2026.
Costs rise steeply with list size because billing counts active profiles.
Usable
Production-ready
Self-hosted server
Cloud service and mobile app
Go, PostgreSQL, Redis, Postfix, Dovecot and Rspamd
Not published
Open source, AGPL-3.0 (network copyleft)
Closed source, sold by Klaviyo
Use inside your business is unrestricted. If you change it and let customers use it over the internet, you must publish your changes.
Closed source: you use it under the maker's terms and cannot change or resell the code.
16k GitHub stars
839 Wikipedia readers a month on phones
Young: started 20 months ago, latest release v4.9.
Not known
Other comparisons
More email marketing and newsletter software
Both sides were judged on 2026-11-03 from makers' descriptions, Wikipedia, READMEs and GitHub data. License, age and popularity lines are worked out directly.