Keila vs Substack
Keila and Substack are both email marketing software. Keila is open source under AGPL-3.0, with 2.3k GitHub stars. Substack is a commercial product from Substack Inc.
Which to pick
- Pick Keila when
- You want a simple self-hosted or EU-hosted alternative to Mailchimp for newsletters.
- Pick Substack when
- A writer wants to start a free or paid newsletter at no upfront cost and benefit from Substack's discovery network.
Side by side
A newsletter tool for managing contacts, signup forms and campaigns, sending through SMTP, SES, Sendgrid or Mailgun.
Newsletter and blog platform with paid subscriptions, podcasts, video and a reader network and app.
Pre-1.0, with a small team and fewer automation features than commercial tools.
It takes 10 percent of paid subscription revenue, and branding and design control are limited.
Usable
Production-ready
Self-hosted server and cloud service
Cloud service and mobile app
Elixir, Phoenix and PostgreSQL
Not published
Open source, AGPL-3.0 (network copyleft)
Closed source, sold by Substack Inc.
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.
2.3k GitHub stars
25k Wikipedia readers a month on phones
Established: started 5 years ago, latest release 0.40.1.
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.