MJML review: free open-source responsive email framework features, pricing (free), how it works, and alternatives compared for 2026.
Category
Email Marketing
Pricing
Open Source, from Free
Verified
Not yet
Last updated
July 18, 2026
Founded
2015
Headquarters
Paris, France (Mailjet, MJML's creator)
APIOpen SourceTemplates
Overview
MJML was created in early 2015 by engineers at Mailjet, the Paris-based email delivery platform, as the internal engine behind their Passport email editor. After a year of internal use, Mailjet open-sourced MJML in 2016 under the MIT license so any developer could use it for free.
The framework solves a long-standing pain point in email development: writing responsive HTML that renders consistently across Outlook, Gmail, Apple Mail, and dozens of other clients traditionally required verbose, table-based markup. MJML abstracts that complexity behind a simple, semantic component syntax.
Key Features
MJML's component model includes tags like mj-section, mj-column, mj-text, mj-image, and mj-button that compile into fully responsive, cross-client HTML with inline CSS automatically. Developers can compile templates via the CLI, a Node package, or the free hosted REST API for server-side rendering without local installation.
Tooling includes an official VS Code extension with live preview, a browser-based playground on mjml.io, and a library of prebuilt templates and components, all of which speed up building and iterating on marketing and transactional email templates.
Pricing
MJML itself is entirely free and open source under the MIT license. The compiler, CLI, VS Code extension, and hosted REST API carry no cost and no usage limits tied to MJML directly.
Mailjet's separate commercial email-sending API and SMTP relay service, used to actually deliver emails rather than compile MJML markup, has its own pricing starting with a free tier for up to 6,000 emails per month and paid plans from roughly 9 dollars per month for higher sending volumes, but this pricing is independent of MJML's free framework.
Key Features
Component-Based Syntax — Semantic tags such as mj-section, mj-column, and mj-button abstract away complex table-based email HTML.
Automatic Responsive HTML Generation — Compiles MJML markup into fully responsive HTML with inline CSS handled automatically.
Free REST API — Hosted API compiles MJML to HTML on demand without requiring any local installation.
VS Code Extension — Official extension provides syntax highlighting and live preview while writing MJML templates.
Cross-Email-Client Compatibility — Generated HTML is designed to render consistently across Outlook, Gmail, Apple Mail, and other major clients.
CLI and Node.js Integration — Command-line tool and Node package allow MJML compilation to be embedded in build pipelines.
Prebuilt Templates and Components — Library of ready-made templates and components speeds up building common email layouts.
MIT-Licensed Open Source Codebase — Fully open source on GitHub, allowing free use, modification, and community contribution.
Pros & Cons
Pros
Free and open source with no vendor lock-in
Dramatically reduces the complexity of hand-coding table-based responsive emails
Backed by an established email company with deep client-rendering expertise
Hosted API lets teams compile MJML to HTML without installing tooling
Large community, template library, and editor tooling such as the VS Code extension
Cons
Requires learning a new markup syntax rather than writing plain HTML and CSS
Generated HTML can be verbose, which may complicate manual debugging
Highly custom or non-standard layouts sometimes still need manual HTML workarounds
No visual drag-and-drop editor is bundled with the open-source framework itself
Relies on community and documentation for support rather than a dedicated commercial help desk
Pricing
Open Source Framework $0 N/A
Frequently Asked Questions
Is MJML free?
Yes, MJML is free and open source under the MIT license, with no paid tiers for the framework itself.
Who created MJML?
MJML was created by engineers at Mailjet in 2015 and open-sourced in 2016.
What does MJML stand for?
MJML stands for Mailjet Markup Language.
Do I need a Mailjet account to use MJML?
No, MJML is an independent open-source framework and does not require a Mailjet account to compile templates.
What does MJML output?
MJML compiles its markup into responsive HTML with inline CSS designed to render consistently across major email clients.
Is there an MJML API?
Yes, MJML offers a free-to-use REST API that compiles MJML markup into HTML programmatically.