MJML
What it is
MJML is an open-source markup language for building responsive email layouts. Its engine converts MJML markup into email HTML built with nested tables and inline CSS, with responsive behavior designed for popular email clients, including Outlook. Reusable, extensible components provide a starting point, and users can create their own components. MJML is free under the MIT license and offers an online editor for writing and rendering markup, as well as a free REST API that renders MJML into responsive HTML. The command-line interface can compile files, watch for changes, and save generated HTML to a selected file. Installation through npm is available on macOS, Linux, and Windows; plugins are offered for Visual Studio Code and Sublime Text, along with a desktop app. API accounts receive an Application ID and two API keys. After rendering, users need an email service provider or shell to send the resulting HTML. The mj-button component is not fully clickable because of email-client support.
For and against
For
- Free and open source under MIT license
- Online editor and REST API are free
- CLI can compile and watch files
- Custom components are supported
- Available through npm on three platforms
Against
- Rendered HTML must be sent separately
- mj-button is not fully clickable
The verdict
MJML focuses on producing responsive email HTML from markup, with several ways to author and compile it. Sending remains a separate step, and its button component has a stated client-support limitation.
Who it suits
MJML suits developers who want a code-first way to create responsive email HTML and can handle sending the rendered output separately. It also offers browser editing, CLI workflows, and an API.
Plans and prices
MJML API
REST API · POST /render · XML or JSON MJML input
Read 15 Oct 2026 · mjml.io
MJML framework and online editor
Open-source engine · browser editor · CLI · plugins
Read 15 Oct 2026 · mjml.io
Free
free-to-use REST API
Read 30 Sep 2026 · mjml.io
On the record
- API
- The MJML REST API is free to use and renders MJML into responsive HTML.mjml.io · read 30 Sep 2026
- API authentication
- Each API account receives one Application ID and two API keys, with public and secret keys intended for browser and back-end use respectively.mjml.io · read 30 Sep 2026
- API response
- API render responses contain generated HTML, the MJML source used, the transpiler version and possible markup errors.mjml.io · read 15 Oct 2026
- Browser SDK
- The mjml-browser package compiles MJML in a browser context and returns generated HTML and diagnostics.github.com · read 15 Oct 2026
- CLI
- The command-line tool compiles files, writes HTML or stdout, watches files, supports minification and can process allowlisted includes.documentation.mjml.io · read 15 Oct 2026
- Client limitation
- The mj-button component is not fully clickable because of email-client support.documentation.mjml.io · read 30 Sep 2026
- Command line
- The CLI can compile files, watch for changes, and write generated HTML to a chosen file.mjml.io · read 30 Sep 2026
- Component model
- Built-in reusable components include sections, columns, text, images, buttons, social elements, accordions, carousels and heroes.documentation.mjml.io · read 15 Oct 2026
- Components
- MJML provides reusable, extensible components and lets users build custom components.mjml.io · read 30 Sep 2026
- Current owner
- LinkedIn describes Mailjet as a Sinch product.linkedin.com · read 15 Oct 2026
- Custom components
- Developers can create and register their own MJML components through configuration files and JavaScript modules.github.com · read 15 Oct 2026
- Desktop app
- The separate MJML App repository distributes an Electron desktop editor with platform-specific releases and source-build instructions.github.com · read 15 Oct 2026
- Documentation depth
- Documentation covers component attributes, CLI options, Node usage, browser usage, JSON input, custom components, tooling and compatibility charts.documentation.mjml.io · read 15 Oct 2026
- Editor integrations
- Official documentation lists Visual Studio Code and Sublime Text plugins, plus Gulp integration and Open VSX availability.documentation.mjml.io · read 15 Oct 2026
- Editor plugins
- MJML offers plugins for Visual Studio Code and Sublime Text, plus a desktop app.mjml.io · read 30 Sep 2026
- Independent score
- FAUN.dev gives MJML an 83/100 community score, with strongest results for pricing transparency and maturity and weakest results for components and templating.faun.dev · read 15 Oct 2026
- Installation platforms
- The official download instructions support installation with npm on macOS, Linux and Windows.mjml.io · read 15 Oct 2026
- Integrations
- The documented ecosystem includes Mailjet, Parcel, IntelliJ IDEA, Gradle, Neos CMS, and Easy-email.documentation.mjml.io · read 30 Sep 2026
