Overview

MJML is a code-first markup tool for developers and teams building responsive email templates. Its component model reduces the amount of email-specific HTML authors need to write, though it is not a visual design workflow or a sending service.

Authors write MJML, then its engine renders HTML built with nested tables and inline CSS for popular email clients, including Outlook. Reusable components encourage consistent layouts, and custom components let teams extend the system. MJML has been open source under the MIT license since 2015.

The boundary matters: MJML produces the template, not the campaign delivery. The rendered HTML must be sent through an email service provider or directly from a shell.

Key features

Responsive rendering: The engine handles the table-based markup and inline styling commonly required for email HTML. That makes MJML useful when a team wants to work in a higher-level markup language rather than maintain that output by hand; it does not remove client-specific limitations.
Reusable components: Built-in and custom components support repeatable layouts and project-specific extensions. This is a better fit for developers who value structured, reusable code than for designers seeking a drag-and-drop canvas.
Flexible authoring: The free online editor can write and render MJML. Local installation through npm works on macOS, Linux, and Windows, while plugins are available for Visual Studio Code and Sublime Text alongside a desktop app.
CLI and API: The command-line interface can compile files, watch for changes, and write HTML to a chosen file. The free REST API also renders MJML into responsive HTML; each account receives one Application ID and two keys, with public and secret keys intended for browser and back-end use respectively.
Include safeguards: Includes are ignored by default. When enabled, include paths are limited to approved roots with canonical boundary checks, a useful constraint for projects that rely on includes.
Rendering is not delivery: MJML leaves sending to an email service provider or a shell-based workflow, so teams needing a single tool for template creation and campaign delivery will need another solution.
Button caveat: The mj-button component is not fully clickable because of email-client support. That limitation can affect calls to action and should be considered before standardizing on the component.

Pricing

MJML is free to use. The Free plan costs 0.00 USD per free and includes the free-to-use REST API. The online editor is also free, and the open-source MIT license provides a path to local use and extension without a paid tier.

There is no paid plan to weigh against the free option. The trade-off is operational rather than tier-based: MJML covers markup and rendering, while sending requires an external provider or shell workflow. Its documented ecosystem includes Mailjet, Parcel, IntelliJ IDEA, Gradle, Neos CMS, and Easy-email.

Platforms

MJML is available on the web, through an API and editor extension, and on Linux, macOS, and Windows. Local npm installation, the CLI, editor plugins, and desktop app give developers options to fit an existing coding setup.

Who it's for

MJML suits developers and teams comfortable with markup who need reusable email layouts and a repeatable rendering workflow. It is less suitable for people who want to design visually without code, or who expect the same product to render and send email. Support and community participation are available through hi@mjml.io, Slack, and GitHub.

Pros and cons

Pros

Free across core workflows: The online editor and REST API are free, and the MIT-licensed project can be installed locally.
Fits development workflows: CLI compilation and file watching, editor plugins, and custom components support teams building and maintaining templates as code.
Structured output: MJML generates nested-table, inline-CSS HTML intended for popular email clients, including Outlook.

Cons

Requires code: MJML is code-first, so it does not serve readers looking for a visual email-design workflow.
Delivery is separate: Rendering does not send messages; an email service provider or shell-based sending process is still required.
Button behavior is constrained: The mj-button component is not fully clickable due to email-client support.

Alternatives

For a visual email-building workflow, consider Blocks Edit, which offers web access, a free plan, and paid collaboration options. Its Collaborate plan is 20.00 USD per year, billed yearly, with 250 GB storage; the 5 users plan is 99.00 USD per year, billed yearly. Choose it when those visual and collaboration options suit better than MJML's code-first workflow.

Dragble is a web, API, and self-hosted option with a free plan capped at 3 projects, 10 GB storage, 10 core content blocks, and Dragble branding. It may fit better when those project and storage limits meet your needs and you prefer its content-block workflow.

MailEditor offers web, API, and extension access. Its Starter plan is 9.00 USD per month, billed yearly, and includes 2 members, 100 HTML exports, 50 ESP exports, 200 test emails, 60 saved templates, 700 MB storage, 10 AI templates, and 30 p. It is a candidate when export and test-email allowances are more relevant than MJML's code-rendering focus.

Postcards has web, API, and extension access; its free Start plan allows 10 template projects, 5 monthly exports, 10 daily test emails, unlimited teammates, and 0 AI credits per month. It may suit a team that wants a free visual template workflow with those export limits.

Serious Email Studio is web-based and includes responsive previews on its free plan, capped at 1 user, 3 projects, and 10 templates. It is worth considering when those project limits and preview workflow fit better than authoring markup.

Stripo is a web and API option whose free plan allows 2 members, 4 monthly exports, 5 daily test emails, and 10 stored emails. It may fit teams prioritizing that web-based export and test-email workflow.

Unitpost offers a free plan with monthly email, daily email, contact, domain, webhook, and hosted-image-storage caps. It is a better direction to consider when those sending-oriented limits align with the need, rather than MJML's template rendering role.

Unlayer is available on web, API, and self-hosted deployments, with a free plan covering email, page, popup, and document builders. It may be a better fit when a broader builder set matters more than MJML's markup-first approach.

Browse more options in Email Template Software and Email Design Software.

Verdict

Choose MJML if you want a free, extensible code-first route to responsive email HTML, with editor, CLI, and API options that fit developer workflows. Look elsewhere if you need visual authoring or sending built into the same product, or if the mj-button limitation is unacceptable for your calls to action.

	MailLayers	MJML
Free plan	Yes	Yes
Free trial	No	No
Paid from	Free	Free
Open source	No	No
Platforms	Web	api, extension, Linux, macOS, Web, Windows
Free plan	Yes	Yes
Editor type	drag-and-drop	code-first
Reusable content blocks	Yes	Yes
HTML export	Yes	Yes
Custom code editing	—	Yes
Custom fonts	—	Yes

MailLayers vs MJML

MailLayers

MJML