“1. Buttondown Best for a developer-centric newsletter backend. Particularly attractive for SaaS integrations, custom signup flows and complete programmatic control. My first choice for API simplicity”
“arguably the cleanest API-first newsletter platform”
“Excellent developer experience”
“API access: including the free plan.”
“Multiple API keys with separate permissions.”
“Buttondown provides a relatively unified API for both subscribers and newsletter emails.”
“2. beehiiv Best if you want a modern newsletter publishing platform with subscriber management, post creation and growth-oriented features. My choice for newsletter publishing”
“good for growth-oriented newsletters”
“Segmentation: supported.”
“beehiiv exposes publication-oriented resources, including posts and subscriptions.”
“One caveat: API access requires account verification, and some capabilities are restricted by subscription tier.”
“3. Ghost Best if you want to build your own publishing experience, control the website and automate content creation. Particularly powerful when self-hosted. My choice for headless publishing”
“excellent for headless publishing”
“The Admin API is particularly interesting if you want to generate and publish newsletter articles programmatically.”
“The important distinction is that the Content API key cannot publish anything. You need the private Admin API key for write operations.”
“4. MailerLite Best for conventional marketing automation, subscriber segmentation, campaign management and reporting. My choice for conventional email marketing”
“very good general-purpose marketing API”
“The API uses a conventional REST structure and is relatively straightforward to integrate into backend applications.”
“MailerLite lets you manage subscribers and campaigns independently.”
“Substack — not a good choice for API-driven publishing”
“However, it does not offer a generally available, documented REST API with API-key authentication for full subscriber and publishing management.”
“Unofficial libraries also exist, but relying on them means depending on undocumented interfaces.”
“Campaign Monitor | Yes | Yes | Yes | Yes”
“3. Kit (formerly ConvertKit) — strong creator-focused API”
“strong creator-focused API”
“It is a genuine REST API rather than an integration-only offering.”
“5. Mailchimp — mature, extensive marketing API”
“Mailchimp's Marketing API is well-established and has broad functionality.”
“The main drawback is complexity. Its API revolves around audiences, campaigns, templates and marketing workflows, rather than a simple newsletter publishing model.”
“Also, API keys grant full access to the associated account, so they must be kept server-side.”
“7. Brevo — broader marketing and messaging infrastructure”
“It is a good choice if your application needs to combine newsletters with transactional emails, SMS and other communications.”