In this article, you can learn more about how several documentation projects can be combined and presented to the reader on the same website.

Read the Docs can be configured to make other projects available on the website of the main project as subprojects. This allows for documentation projects to share a search index and a namespace or custom domain, but still be maintained independently.

This is useful for:

  • Organizations that need all their projects visible in one documentation portal or landing page

  • Projects that document and release several packages or extensions

  • Organizations or projects that want to have a common search function for several sets of documentation

For a main project example-project, a subproject example-project-plugin can be made available as follows:

See also

How to manage subprojects

Learn how to create and manage subprojects

How to link to other documentation projects with Intersphinx

Learn how to use references between different Sphinx projects, for instance between subprojects

Sharing a custom domain

Projects and subprojects can be used to share a custom domain. To configure this, one project should be established as the main project and configured with a custom domain. Other projects are then added as subprojects to the main project.

If the example project example-project was set up with a custom domain,, the URLs for projects example-project and example-project-plugin with alias plugin would respectively be at:

Using aliases

Adding an alias for the subproject allows you to override the URL that is used to access it, giving more control over how you want to structure your projects. You can choose an alias for the subproject when it is created.

You can set your subproject’s project name and slug however you want, but we suggest prefixing it with the name of the main project.

Typically, a subproject is created with a <mainproject>- prefix, for instance if the main project is called example-project and the subproject is called plugin, then the subproject’s Read the Docs project slug will be example-project-plugin. When adding the subproject, the alias is set to plugin and the project’s URL becomes

When you add a subproject, the subproject will not be directly available anymore from its own domain. For instance, will redirect to

Custom domain on subprojects

Adding a custom domain to a subproject is not allowed, since your documentation will always be served from the domain of the parent project.

Separate release cycles

By using subprojects, you can present the documentation of several projects even though they have separate release cycles.

Your main project may have its own versions and releases, while all of its subprojects maintain their own individual versions and releases. We recommend that documentation follows the release cycle of whatever it is documenting, meaning that your subprojects should be free to follow their own release cycle.

This is solved by having an individual flyout menu active for the project that’s viewed. When the user navigates to a subproject, they are presented with a flyout menu matching the subproject’s versions and Offline formats (PDF, ePub, HTML).