Overview

MJML is best suited to developers and teams who want to build responsive email layouts in markup rather than a visual editor. Its free rendering tools and extensible components make it a practical way to produce email HTML; it stops before delivery.

Instead of writing email layout tables and inline styles directly, authors work in MJML and compile it into HTML designed for popular email clients, including Outlook. The component approach offers reusable structure, while custom components give teams room to adapt it. MJML has been open source under the MIT license since 2015.

Key features

Responsive email output: The engine generates HTML with nested tables and inline CSS. That lets developers work at a higher level than the output markup, though the mj-button component is not fully clickable because of email-client support.
Reusable, extensible components: Built-in components and the ability to create custom ones suit teams that want consistent, code-managed templates. This is less compelling for people who prefer to lay out emails visually.
Flexible authoring: Users can write and render MJML in the free online editor, install it through npm on macOS, Linux, or Windows, or use plugins for Visual Studio Code and Sublime Text. A desktop app is also available.
CLI and API rendering: The CLI compiles files, watches for changes, and writes generated HTML to a chosen file. The free REST API also renders MJML; each account gets one Application ID and two API keys, with public and secret keys intended for browser and back-end use. MJML ignores includes by default and limits enabled include paths to approved roots with boundary checks.
Integration and community: The documented ecosystem includes Mailjet, Parcel, IntelliJ IDEA, Gradle, Neos CMS, and Easy-email. Users can contact MJML by email or take part through Slack and GitHub.

Pricing

MJML is free to use, including its REST API. The Free plan costs 0.00 USD per free. There is no paid tier described, so teams choosing MJML do not have to weigh feature access against a subscription price.

The trade-off is scope rather than price: MJML renders templates but does not send them. After compilation, users must deliver the HTML through an email service provider or directly from a shell, adding a separate step for anyone seeking an all-in-one workflow.

Platforms

MJML is listed for API, extension, Linux, macOS, web, and Windows use. The online editor provides a browser-based route, npm supports local installation on macOS, Linux, and Windows, and editor plugins support Visual Studio Code and Sublime Text. A desktop app is also offered.

Who it's for

MJML fits developers and teams comfortable with code who need reusable email layouts and control over generated HTML. The CLI suits file-based workflows, while the API supports rendering from browser or back-end applications. It is not the right fit for readers who need email sending built into the same product, or who want to create layouts without markup.

Pros and cons

Pros

Free authoring and rendering: The online editor, local tooling, and REST API let teams choose a workflow without a listed subscription cost.
Structured output: MJML compiles components into responsive email HTML, avoiding direct authoring of the nested tables and inline CSS it generates.
Extensible markup: Custom components help teams build on the reusable component system rather than rely only on its built-ins.

Cons

Delivery is separate: MJML produces HTML but leaves sending to an email service provider or shell-based process.
One component has a client constraint: The mj-button is not fully clickable across email clients.
Code-first workflow: Markup is central to MJML, making it a poor match for readers seeking a visual designer.

Alternatives

For a browser-based email design workflow, compare Email Design Software and Email Template Software.

Canary is an email client with a free plan that includes inbox features and templates, making it a different option for managing email rather than compiling markup. Beefree (now RGE Studio) offers a web-based design tool with a free Starter plan capped at 10 designs and 6 exports per month; consider it when those visual-design limits fit the work. Blocks Edit is another alternative to consider.

Dragble offers web, API, and self-hosted access, with a free plan limited to 3 projects and 10 GB of storage. Unlayer provides web, API, and self-hosted options; its free plan includes email, page, popup, and document builders. EmailBuilder.ai has a web-based free Playground plan capped at 10 emails, 3 templates, 50 AI Assistant calls, and 5 sends or exports. MailForge is a web option with a free plan allowing 5 exports per month, 3 projects, and HTML and MJML export. Parcel offers a web-based free Community plan with 50 emails and 50 snippets, plus HTML problem checking, test sends, previews, and accessibility testing.

Verdict

Choose MJML if you want a free, code-first way to create responsive email HTML from reusable markup, especially when you need local, CLI, or API rendering. Look elsewhere if you need visual-first design or email delivery in the same tool.

	MJML	Mosaico
Free plan	Yes	Yes
Paid from	Free	Free
Platforms	api, extension, Linux, macOS, Web, Windows	self-hosted, Web
Free plan	Yes
Editor type	code-first
Reusable content blocks	Yes
HTML export	Yes
Custom code editing	Yes
Custom fonts	Yes
Custom HTML editing		Yes
Export options		html

MJML vs Mosaico

MJML

Mosaico