Single-tenant or multi-tenant: which architecture for a SaaS application?
Updated: 2026-11
Multi-tenant with a shared application and cleanly separated data is the more economical choice for most SaaS products: one operation, one update, lower cost per customer. Single-tenant pays off when individual customers require their own instance by contract or regulation, need heavy customisation or generate very different loads.
The tenancy question comes early and is expensive to change later. It determines operating costs, security model, update process and how customers access their data.
Hybrid forms exist: a shared application with separate databases or schemas per customer, or multi-tenant as standard with dedicated instances for a few large customers.
Head to head
| Criterion | Single-tenant | Multi-tenant |
|---|---|---|
| Operating costs | Higher, one instance per customer. | Lower, infrastructure is shared. |
| Updates | Per customer; versions can drift apart. | Once for everyone. |
| Data separation | Physically separate. | Logically separate, for example with row level security; must be enforced consistently. |
| Customisation | Customer-specific changes possible. | Configuration instead of code per customer. |
| Regulation | Eases requirements for own instance or location. | Requires evidence of separation. |
| Scaling | Controllable per customer. | Shared; noisy neighbours must be limited. |
When Single-tenant wins
- —Customers contractually require their own instance or a specific data location.
- —Individual customers need deep customisation that configuration cannot cover.
- —The number of customers is small and their volume large.
When Multi-tenant wins
- —The product targets many small and medium customers with similar requirements.
- —Fast releases for all matter more than customer-specific versions.
- —Data separation can be implemented and verified technically.
Our take
For most SaaS products in the SME space, multi-tenant with tenant isolation at database level is the right start. Our own products use row level security in Postgres for this.
If you know early that some large customers will need their own instance, design the architecture so this option remains possible later without forking the product.
Parent service: SaaS Product Development
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FAQ
Is multi-tenant less secure?
Not inherently. What matters is that separation is enforced consistently at database level and checked regularly.
Can you switch later?
From multi- to single-tenant for individual customers yes, if the architecture allows it. The reverse is usually a bigger rebuild.
What about data export on cancellation?
In both models a complete export per customer should be possible; it is also a question of data portability.