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The same editor and rendering engine behind Maildeno are also available as open-source, MIT-licensed npm packages — no account, no API key, and no network access required.

Package What it does Version

@maildeno/editor

The drag-and-drop email editor as an embeddable component.

0.4.9

@maildeno/renderer

Renders a template JSON file to HTML, MJML, or React Email — entirely offline.

0.2.0
Both packages are fully functional with zero Maildeno backend — every export target, template storage, and version history work out of the box using the browser’s localStorage. Connecting to Maildeno’s hosted platform (cross-device template sync, team collaboration, an image CDN, send analytics) is entirely optional, and is a one-line change — swapping in a different storage adapter — if you decide you want it.

How this relates to the hosted product

This site documents two ways to use Maildeno, and it’s worth being explicit about which one each part of the sidebar covers:

  • Open Source (this section) covers the packages you run yourself. No dashboard, no API key, no data leaving your infrastructure unless you choose to connect it.

  • Email Builder and SDK Reference cover the hosted platform — the dashboard at maildeno.com/login and the Render API/SDKs that talk to it. This path needs a Maildeno account and an API key.

Open source (self-hosted) Maildeno (hosted)

Editor

@maildeno/editor embedded in your own app

Dashboard at maildeno.com/login

Template storage

localStorage by default (pluggable storage adapter)

Cloud sync, team collaboration, version history

Rendering

@maildeno/renderer, fully offline

Render API + SDKs (JS, Python, PHP)

Images

Hosted wherever you already host assets

Built-in image CDN

Account / API key

Not required

Required

License / cost

MIT — free

Free tier, then paid plans

Mix and match

The editor, the renderer, and the hosted Render API all read and write the same template JSON format, so you aren’t locked into one path:

  • Design in the open-source editor, render locally with @maildeno/renderer — nothing ever touches Maildeno’s servers.

  • Design in the open-source editor, but render with a hosted SDK by uploading the exported JSON through your own backend.

  • Design in the hosted dashboard, export the template as JSON, and render it offline with @maildeno/renderer — useful for CI, air-gapped environments, or just avoiding a runtime API call.

Where to go next