The verdict in three sentences
For a SaaS startup in Amsterdam targeting SMEs first, a shared database with tenant-ID isolation remains the best cost-to-speed ratio in 2026. Once enterprise accounts enter the pipeline, plan a hybrid architecture able to move a customer to a dedicated schema or database, for a development premium of 10 to 30%. The choice must be made before the first line of business code: changing it after 18 months costs 3 to 5 times more.
The three multi-tenant models compared
Multi-tenancy means serving several customers (tenants) with the same application. The difference lies in how strongly their data is isolated.
| Criterion | Shared database (tenant_id) | Schema per customer | Dedicated database per customer |
|---|---|---|---|
| Initial development premium | Baseline | +10 to 15% | +20 to 30% |
| Infrastructure cost per customer per month | EUR 0.5 to 1 | EUR 1 to 2 | EUR 2 to 3 and up |
| Data isolation | Logical (RLS, filters) | Strong | Complete |
| Comfortable number of customers | 10,000 and more | 500 to 2,000 | 50 to 300 |
| Per-customer backup and restore | Complex | Simple | Native |
| Schema migrations | 1 pass | N passes | N passes |
| Best fit | SMEs, freemium | Mid-market, regulated sectors | Enterprise, health, finance |
With PostgreSQL, Row Level Security makes the shared database far more robust than five years ago: a query missing a filter no longer leaks another customer's data if the policies are set correctly.
What setup costs in 2026
The amounts below are 2026 orders of magnitude for a startup building its product with a team of 2 to 4 developers or an outside vendor.
| Multi-tenant component | Estimated cost excl. VAT | Timeline |
|---|---|---|
| Data model and RLS policies | EUR 3,000 to 6,000 | 1 to 2 weeks |
| Tenant management (creation, plans, suspension) | EUR 2,500 to 5,000 | 1 week |
| Multi-organization authentication and SSO | EUR 3,000 to 8,000 | 1 to 2 weeks |
| Per-tenant backup and export | EUR 2,000 to 4,000 | 1 week |
| Routing to a dedicated database (enterprise option) | EUR 4,000 to 10,000 | 1 to 2 weeks |
| Per-tenant observability (logs, quotas) | EUR 1,500 to 3,500 | 0.5 to 1 week |
| Total multi-tenant foundation | EUR 12,000 to 36,000 | 3 to 6 weeks |
Infrastructure stays modest at first: a managed PostgreSQL database at a European provider starts around EUR 50 to 150 per month and handles several hundred SME customers.
The isolation enterprise buyers require
Enterprise security questionnaires almost always ask the same things: where is my data, who accesses it, can I retrieve it and have it deleted, can you restore only my workspace without touching others? A shared database without per-tenant export answers the last question poorly.
| Enterprise requirement | Shared database answer | Hybrid architecture answer |
|---|---|---|
| Physically isolated data | No | Yes, dedicated database as an option |
| Restore only their workspace | Ad hoc script, 1 to 3 days | Native, under 4 h |
| Customer-specific encryption key | Difficult | Possible |
| Hosting in a specific region | Shared by all | Per customer |
| Acceptable price for the option | Not applicable | +EUR 300 to 1,500 per month billed to the customer |
The practical rule: sell the dedicated database as a premium option. It costs EUR 2 to 3 a month in raw infrastructure, but operations and repeated migrations justify a surcharge of several hundred euros.
Mini case study
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Léa, CTO of an Amsterdam startup building scheduling software for transport companies, expects 400 SME customers within 18 months and has 3 enterprise accounts in talks. She chooses a shared database with RLS plus a dedicated-database option: a EUR 26,000 foundation over 5 weeks, a 22% premium on an MVP priced at EUR 118,000.
Infrastructure: 400 customers at EUR 0.8 per month comes to EUR 320, plus 3 dedicated databases at EUR 3 of infrastructure, each billed EUR 900 per month to the enterprise accounts. The EUR 2,700 of monthly options pays back the EUR 26,000 premium in under 10 months, and the first enterprise contract would not have been signed without that isolation.
FAQ
Can you start with a shared database and migrate later?
Yes, if every table carries a tenant ID from day one and queries go through a common layer. Without that discipline, migrating at 18 months often costs EUR 40,000 to 80,000.
Is a shared database GDPR-compliant?
Yes, GDPR does not require physical isolation. It requires appropriate measures, which RLS, encryption and logging cover in 90% of SME cases.
How many customers can a shared PostgreSQL database handle?
A properly indexed instance easily serves 5,000 to 20,000 SME tenants. Partitioning or sharding usually only becomes necessary beyond 1 TB of data.
How long does a full multi-tenant foundation take?
Allow 3 to 6 weeks depending on SSO and the dedicated-database option. The core alone, without SSO, fits in 3 weeks.
Do you need one microservice per function?
Rarely at the start. A modular multi-tenant monolith is 30 to 50% cheaper to evolve during the first two years.
Let's scope your project. We design your multi-tenant SaaS foundation, shared or hybrid, for EUR 12,000 to 36,000 delivered in 3 to 6 weeks. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
