What is multi-site/ multi-domain?

CiviCRM has built in support for multisite access - several separate sites accessing the same CiviCRM database. (this is different to the Drupal concept which means shared codebase). In most cases a site will be defined by a distinct URL

These sites could be

CiviCRM has no idea which of these configurations you are using & does not need to know

You can select from different levels of multisite-ness


Separate domain records but the database is not configured as a mutlisite

This basically means you specify the domain in your civicrm.settings.php file. CiviCRM is not really aware of this. Where a table is domain specific it will select the rows that relate to that domain.
Separate domain records with the site configured as a multisiteIn addition to the above you select the box that defines the site as a multisite and specify a domain group. Contacts created on this site will be added to this group & groups created on this site will be made sub-groups of this group or associated with the group via a shared group organisation. You do not need to make the top level site multisite-aware unless you specifically want contacts on that site to be added to a group (large hierarchical groups can affect performance)

Separate domain records with multisite permissioning

By installing the multisite module on top you cause people on each domain who don't have 'view all contacts' permission or 'edit all contacts' to only see contacts in that domain

Multisite versus Settings Management

Since 4.1 it has been possible to manage having different urls & other settings per site by over-riding settings (those which are stored in civicrm_settings.php) in the civicrm.settings.php file

Setting overrides can handle


Use different domains if you want

- domain specific membership types

- domain specific payment processors

- domain specific different from addresses from CiviMails

- domain specific link back URLS in CiviMails

- domain specific domain contact details

Multilevel permissioning behaviour

This permissioning is delivered by the the multisite extension. The extension also helps manage a shared user table (even if you turn permissioning off by setting domain group to 0)

Multilevel permissioning  lends itself very well to a head office branch or chapter organisation as the functionality is hierarchical. The users of the Head Office site can see all the users from all the sub-sites. Users logged into Branch site 1 cannot see users from Branch site 2 unless they have 'view all contacts', 'edit all contacts' or  'administer multisite' permissions. Likewise users logged into branch 2 cannot see Branch 1 users unless they have the extra drupal permissioning. The Head Office users can see both.

The mechanism behind it is groups. Each domain has a domain group (with the likely exception of the top level domain). This group has 'associated groups'. The associated groups are either child groups or groups that share the same group organisation. The preferred method is to share a group organisation as there are less performance costs & there is less potential for confusion. A good use-case for a child group is when you want to add another level to your multisite set up. These level 3 sites will be members of their parent site in a hierarchical organisation.

You should avoid setting up smart groups as child groups. Permissions are only based on 'hard-add's to the group. When a person views a smart group that is an associated group they will see the interesection of that group & contacts that have been hard-added to the parent group or an associated group. However, the site will still incur the performance cost of calculating the whole smart group. In addition, if it is a child group the site will incur the performance cost of storing all the contacts of the child group against the parent group. If a user with 'view all contacts' permission views the site group they will see all the contacts of site group and all child groups INCLUDING smart groups - so what they see when they look at this site group will NOT reflect the contacts that are visible from that site. There may be situations where this makes sense - but in general it increases confusion.

It is possible for a group to be a child of more than one group in which case it will be considered to be in both those groups and can be seen from the site of both those groups.

If the multilevel permissioning module is enabled:


Components of multisite functionality


Delivered by









Various settings, urls can be domain specific,

CiviCRM Core - Settings table

This can be configured by domain or overridden at runtime in the civicrm.settings.php file - the latter is a good approach when only settings are dependent on the domain being accessed as it is simpler

Works well in general.


payment processors are domain specificCiviCRM Core

Based on domain_id in payment processor table

Domain_id set in civicrm.settings.php

Domain contact details are domain specificCiviCRM CoreBased on the contact_id in the civicrm_domain table  

Navigation is domain specific

CiviCRM Core

Domain_id set in civicrm.settings.php

Works well except for WRT upgrades

A couple of upgrade issues are open on this

Reports are Domain specific

CiviCRM Core

Domain_id set in civicrm.settings.php

Works well in general

Upgrades are hit & miss on whether they update these correctly

Group Organization field is exposed

CiviCRM Core Multisite functionality

Domain_id set in civicrm.settings.php




 is_enabled is set to 1

Works fine, allows group to be set


Group can be linked to multiple orgs in the schema but only single in the UI


Contact is added to the group associated with the domain they are created on

CiviCRM Core Multisite functionality

Domain_id set in civicrm.settings.php


multisite domain group is specified




 is_enabled is set to 1

Works well  in general



Pete has identified that contacts created via current employer mechanism aren’t always added

Parent ID is compulsory for any group created


This is implemented in 2 ways.


People with the permission to ‘administer multiple organisations’ can choose the parents


For others the parent will automatically be set to the domain group of the site it is created on

CiviCRM Core Multisite functionality - note that the parent ID OR the organisational contact_id is required in the latest version of the extension

Domain_id set in civicrm.settings.php


multisite domain group is specified


multisite is_enabled is set to 1

There are 3 possible scenarios for these nested groups

1)      The child group is a non-smart group and only contains contacts also in the parent group. In this case the nesting will have no effect on the membership of the parent group

2)      The child group is a non-smart group and contains contacts (intentionally or otherwise) not in the child group. The parent group is extended to include these contacts (not hard-added). Contacts added to this type of group extend the ACL visibility for those permitted to see this group


3)      Child group is a smart group. Child group criteria extend the parent group. However this extended group is restricted by ACLs. Hence smart groups do not extend any ACLs that apply to the parent group (in core or in code)

This group nesting is problematic as it creates a large load in terms of creating the group_contact_cache entries of 2-3 levels of parent groups and resolving the smart group cache. Using the latest version of the extension & using group organisation for linkages will mitigate this. You can still use the hierarchical approach where you want to build up a hierarchical group for other purposes (e.g. mailing)


Changes to groups frequently cause time outs & server load as the group cache is rebuilt for the parent group – inclusive of resolving every child smart group.



Parent group is optional IF group organisation is set

Multisite dev version of extension introduces this


Contacts without ‘view all contacts’ permission but with ‘view all contacts in site’ are allowed to see all contacts in the domain group

CiviCRM multisite extension

Domain_id set in civicrm.settings.php


multisite is_enabled is set to 1


multisite domain group is specified


ACL_is_enabled is set to 1

Permission is based on hard-adds to the domain group. WRT the 3 scenarios above

1)      The addition of contacts to both parent and child groups is redundant

2)      Hard adds to child groups extend the parent group and are useful where this is the intention (e.g. a child group that represents a sub-site.

3)      Smart groups. Smart groups are cached in their entirety, both for the smart group and any parents it may have. This creates a lot of work. However, on their way out they are filtered according to the previous 2 items.

From a contact viewing permissioning point of view this suggests that only where #2 applies the group nesting is useful.


As an aside  - the multisite extension currently works on an either or basis with other ACL hooks. Hence a contact can either view all contacts in domain OR have other code based ACLs applied.  Some thought should go into desired behaviour when both are in use

Contacts without ‘view all contacts’ permission but with ‘view all contacts in site’ are allowed to see all groups within the site

CiviCRM multisite extension

Domain_id set in civicrm.settings.php


multisite domain group is specified



multisite is_enabled is set to 1


ACL_is_enabled is set to 1

This is currently tied with the group nesting & those groups that are children of the site group are visible. However, as seen above the nesting mechanism should only be used for child groups where it is desirable for hard-adds to that group that are not otherwise part of the domain be included in the parent group – ie. it should be used carefully & deliberately


Potential replacement mechanisms are group_organization & group_type.


Either of these could be used to designate which domains a group should be visible on & either from a schema point of view support many to one, from a UI group_organization only supports one-to-one


Potentially people with ‘administer multiple organisations’ could create global smart groups & specify which sites they appear on.


Those on sub-sites with administer civicrm could specify if the group is available on child sites.



See Proposed changes to multisite

There is a general problem in that the civicm ACLGroup hook is inconsistently applied in core – see


Shared User Table handling

Multisite extension

Extension enabled

UF_matches are updated where the user name name is the same on multiple domains. The multisite extension will manage this when enabled even when multisite & acls are turned off


Functional Separation in Multisite

Is separated



NoHOWEVER, the multilevel 'multisite' module adds ACLs that do provide segregation  

 contact related entities-


address, phone etc





personal contribution page





The multisite concept only limits access to this data by ACLs - one implementation is the 'multisite' Multilevel module.


grantPossiblysee notes with option value  
membership type



Options for Membership types not owned by a given org appear on the membership search page. However the user will not find any members while searching using these options if they don't belong to their organisation

Contribution form will allow a membership type belonging to another org to be included. But if someone signs up they are not automatically added to the other org

L2 site manager can see memberships from other organisations and 'appears' have permission to change which site a membership type belongs to (although this fails per item above) 




membership statusnoit would be more generally useful for this to be by membership type than by domain per se  
payment processoryes   
Contact type & subtypeno   
Contribution typeno(in multi-country models this might be desirable whereas national organisations are likely to think it a bad thing)  
Contribution PagenoDesirable  
Contribution PremiumnoDesirable  
Custom fieldsno   
Dedupe rulesno   
Financial Accountno   
Groupsort-ofGroup visibility is dictated by the multilevel module if installed.  
Scheduled jobsyesbeware - your mails won't go out if you don't configure for all domains  
Location typeno   
Domain locationyesie. street address etc for your organisation is per domain  
Mailingyesthese are per domain - not quite if there is impact of this other than that it knows to send out the crons from the right site - thereby getting the permissions right  
Mail settingsyespop / smtp / from addresses are per site  
Import & export mappingsnoDesirable  
Menu & navigationyesThis is fairly problematic as, at least on the upgrade to 4.1, only the main site menu was upgraded  
Message templatesno   
Logos & headersno


This isn't something currently storable in Civi & to add your logo / header to workflow templates you need to edit all the individual templates but to support multisite we need to look at storing logos & headers so a smarty token can signify them

Option groups & option valuespartiallyThe option value has a domain id. It doesn't seem to be heavily used - ie. I found mail approval, grant_types & from_email_address to be the only ones with domain ids. But this seems like it might be a good angle for events & others - eg. if the event_type_id is for that domain or has no domain then show on the page.  
Price setspartiallyThe price sets themselves are but not the price fields & values - which makes the idea of having one price set which shows different fields on each site impossible.  
Relationship typeno   
Report instancesyes   
Smart groupspartiallyIf multilevel permissioning is installed then permission to view groups in other parts of the hierarchy is restricted by ACLs  
Settingsyesthe CiviCRM settings table is domain specific  
Status PreferencesyesCiviCRM 4.7+  
UsersyesUsers are separately matched to civicrm contacts by domain