Run multiple sites from a single SilverStripe install.

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CI Silverstripe supported module


composer require silverstripe/subsites


The subsites module provides a convenient way of running multiple websites from a single installation of SilverStripe, sharing users, content, and assets between them - the sites will be managed from a single CMS.

A useful way to think of its use is where you have a business with a global headquarters and four branches in various countries. The subsites module allows the five offices to use a single Silverstripe installation, and have information from the headquarters flow down into the branches. The branches can hold information that is individual and the website templates can also be different.

All separation of content achieved with this module should be viewed as cosmetic and not appropriate for security-critical applications. The module gives some control over access rights especially in the "Pages" and "Files" area of the CMS, but other sections' separation is much weaker: for example giving someone any of the "Roles and access permissions" will imply that the person will likely be able to escalate his/her privileges to the global admin role.

For user documentation please see:

  1. Setting up subsites
  2. Working with subsites

Features & limitations


  • Each subsite appears as a standalone website from a users prospective
  • No need to duplicate existing code as all subsites use the same codebase as the main site
  • You can set individual permissions on each subsite domain name
  • Ability to copy a page and its content from the main site into a subsite
  • Create translations of subsite pages
  • Schedule the publishing of subsite pages
  • The database is shared between subsites (meaning duplicating content is easy)
  • When recovering from a disaster it's much easier to bring up a new copy of a single environment with 100 subsites than it is to bring up 100 environments.


  • Subsites are usually accessed via their own separate domains. In order to allow efficient cross-subsite CMS editing, they can also be accessed via URL parameters rather than domain maps. This can weaken domain-specific security controls in your environment such as domain-specific IP whitelists, firewall rules or business logic.
  • Each subsite domain name has to be set up on the server first, and DNS records need to be updated as appropriate.
  • A subsite cannot use a different codebase as the main site, they are intrinsically tied
  • The only code a developer can edit between subsites is the theme
  • The separation between subsites in the CMS needs to be seen as cosmetic, and mostly applicable to the "Pages" and "Files" sections of the CMS.
  • All subsites run in the same process space and data set. Therefore if an outage affects one subsite it will affect all subsites, and if bad code or hardware corrupts one subsite's data, it's very likely that it has corrupted all subsite data.
    • This principle applies to application error, security vulnerabilities and high levels of traffic
  • It is not currently possible to backup or restore the data from a single subsite.
  • It is awkward (but not impossible) to have separate teams of developers working on different subsites - primarily because of the level of collaboration needed. It is more suited to the same group of developers being responsible for all of the subsites.

If more isolation of code, security, or performance is needed, then consider running multiple separate installations (e.g. on separate servers).


Strict Subdomain Matching

The module tries to provide sensible defaults, in which it regards and as the same domains. In case you want to distinguish between these variations, set Subsite::$strict_subdomain_matching to TRUE. This won't affect wildcard/asterisk checks, but removes the ambiguity about default subdomains.


Groups can be associated with one or more subsites, in which case the granted page- and asset-related permissions only apply to this subsite.

Note that creating a Subsite-specific group, and giving it permissions unrelated to content editing and asset management will result in members of this group being able to escalate their privileges. An example here is giving that group "Full administrative rights" or some of the "Roles and access permissions", in which case it is possible for the member of that group to simply add himself to the global "Administrators" group or change his own group to having access to all sites.

The subsites module should be viewed as providing a convenience of visual separation for the sites on the interface level, rather than a fully tight security model for managing many sites on the same CMS (it is still the same CMS).

Access created domains

Once you have created some subsites/domains in your admin, you can check the overall functionality of subsites by

In some Browsers the SubsiteID is visible if you hover over the "Edit" link in the search results of Subsite admin.

Subsite-specific themes

Download a second theme from and put it in your themes folder. Open admin/subsites?flush=1 and select one of your subsites from the menu on the bottom-left. You should see a Theme dropdown in the subsite details, and it should list both your original theme and the new theme. Select the new theme in the dropdown. Now, this subsite will use a different theme from the main site.

Cascading themes

Themes will resolve theme files by looking through a list of themes (see the documentation on creating your own theme). Subsites will inherit this configuration for the order of themes. Choosing a theme for a Subsite will set the list of themes to that chosen theme, and all themes that are defined below the chosen theme in priority. For example, with a theme configuration as follows:

    - '$public'
    - 'my-theme'
    - 'watea'
    - 'starter'
    - '$default'

Choosing watea in your Subsite will create a cascading config as follows:

  - 'watea'
  - '$public'
  - 'starter'
  - '$default'

You may also completely define your own cascading theme lists for CMS users to choose as theme options for their subsite:

      - '$public'
      - 'watea'
      - 'starter'
      - '$default'
      - 'my-theme'
      - 'starter'
      - '$default'

Limit available themes for a subsite

Not all themes might be suitable or adapted for all subsites. You can optionally limit usage of themes:



Enable Subsite support on DataObjects

To make your DataObject subsite aware, include a SubsiteID on your DataObject. eg:


private static $has_one = [
    'Subsite' => Subsite::class

Include the current SubsiteID as a hidden field on getCMSFields, or updateCMSFields. eg:


public function getCMSFields() {
    $fields = parent::getCMSFields();
    if (class_exists(Subsite::class)){
        $fields->push(HiddenField::create('SubsiteID', 'SubsiteID', SubsiteState::singleton()->getSubsiteId()));
    return $fields;

To limit your admin gridfields to the current Subsite records, you can do something like this:


public function getEditForm($id = null, $fields = null){
    $form = parent::getEditForm($id, $fields);

    $gridField = $form->Fields()->fieldByName($this->sanitiseClassName($this->modelClass));
        $list = $gridField->getList()->filter(['SubsiteID'=>SubsiteState::singleton()->getSubsiteId()]);

    return $form;

Enable menu support for custom areas in subsites

Custom admin areas, by default, will not show in the menu of a subsite. Not all admins are adapted for or appropriate to show within a subsite. If your admin does have subsite support, or is intentionally global, you can enable the show in menu option either by applying:



or by defining the subsiteCMSShowInMenu function in your admin:


public function subsiteCMSShowInMenu(){
    return true;

Using Subsites in combination with Fluent

When using Subsites in combination with Fluent module, the Subsites module sets the i18n locale to the language defined in the current Subsite. When this behaviour is not desired and you need to use the locale in FluentState use the following setting in your yml config file:

  ignore_subsite_locale: true

Public display of a subsite

By default, each subsite is available to the public (= not logged-in), provided a correct host mapping is set up. A subsite can be marked as non-public in its settings, in which case it only shows if a user with CMS permissions is logged in. This is useful to create and check subsites on a live system before publishing them.

Please note that you need to filter for this manually in your own queries:

$publicSubsites = DataObject::get(
    Subsite::$check_is_public ? '"IsPublic"=1' : '';

To ensure the logged-in status of a member is carried across to subdomains, you also need to configure PHP session cookies to be set for all subdomains:

// Example matching and