Drupal multisite — one platform, multiple websites
When an organisation runs multiple websites — different brands, regions or products — that does not necessarily mean multiple separate platforms.
Drupal is one of the few CMS platforms that supports multisite configuration natively in core. This means a single Drupal installation can serve multiple websites with a shared codebase, shared modules and a shared update process — but with separate content, users and configuration per site.
When multisite makes sense
Works well when:
- The organisation runs multiple structurally similar sites — regional offices, subsidiaries or separate brands
- The sites share functional requirements — common modules, shared design logic, shared integrations
- You want security updates and Drupal version upgrades to happen for all sites at once, not separately
Does not work well when:
- The sites have completely different functionality from each other
- Teams are independent and want full autonomy over their platform
- Performance issues on one site must not affect the others
How Drupal multisite works technically
Drupal identifies which site to serve based on the domain or URL. Each site gets its own:
- Database — content, users and configuration are separate
- Files directory — uploaded files are stored separately
- Configuration — modules, theme and language settings can be configured independently per site
The shared part is the codebase — Drupal core, contributed modules and custom modules. When you update a module, it updates for all sites at once.
Known Drupal sites
Drupal is the choice of many large organisations precisely because it scales well to centralised management — one platform running dozens or hundreds of sites.
University of Tartu — ut.ee A clear Estonian example: UT runs on Drupal and the same platform powers the websites of the university's faculties, institutes and study programmes. One IT team manages the platform while dozens of content editors manage their own sections.
Tallinn University of Technology — taltech.ee TalTech also uses Drupal. The university's structure — multiple faculties, institutes and research groups — fits well with a multisite model where a shared codebase serves different subdomains.
European Union institutions The European Commission (commission.europa.eu), European Parliament sites and other EU institution websites run on Drupal. The EU has built a shared open-source platform called OpenEuropa — built on Drupal and shared across EU institutions. It is one of the largest Drupal-based multisite deployments in the world: a unified codebase, shared design system, dozens of separate sites.
This is a typical use case for large organisations: one IT team manages the platform, dozens or hundreds of content editors manage their own sections.
Practical benefits
Updates — security updates are applied with a single Composer command for all sites at once. With five sites, that means five times less maintenance time.
Shared development — custom functionality is written once and available to all sites. When one site gets a new module, it can be activated on the others easily.
Shared deployment — one CI/CD pipeline, one deploy process, one staging environment.
What needs planning
Database separation — each site needs its own database connection. Simple to configure, but needs to be factored into hosting requirements.
Memory requirements — serving multiple sites simultaneously increases memory usage. Allocate more resources than you would for a single site.
Test coverage — automated tests must cover the critical workflows of all sites. A change to one site could theoretically affect others.
Version management — all sites run the same Drupal version. If one site requires a specific module version, it must be compatible with all others.
Alternative: separate installations
Multisite is not the only way to manage multiple Drupal sites. Separate installations are a simpler solution when:
- Sites update at different times
- Teams are independent
- Functional overlap between sites is small
The downside of separate installations is that security updates must be applied to each site individually — which becomes resource-intensive with a larger number of sites.
Summary
Drupal multisite is a powerful option but requires a thought-through architecture. If an organisation has three or more similar Drupal sites and wants to reduce maintenance costs, multisite is worth considering. For fewer sites, separate installations are often a simpler and more maintainable choice.
If you are evaluating whether multisite fits your situation, describe the setup to us — we can help clarify the architectural decision.
Kaido Toomingas
WebPro Company OÜ
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