The verdict in three sentences
For a B2B SaaS in Singapore in 2026, the shared schema is the best starting point: infra at 150-500 EUR/month for 500 accounts and simple deployment. A per-tenant database reassures demanding enterprise clients but costs 3 to 5 times more to operate and maintain. The winning compromise: shared schema by default, a premium dedicated-database option for clients who pay for it, while designing for isolation from day one to avoid a 20,000-60,000 EUR refactoring.
The three isolation models compared
The multi-tenant architecture choice boils down to a slider between cost and isolation. Three models dominate the B2B market, from most pooled to most segregated.
| Model | Isolation | Infra cost (500 accounts) | Operating complexity |
|---|---|---|---|
| Shared schema (tenant_id) | Logical | 150 - 500 EUR/month | Low |
| Schema per tenant (same DB) | Medium | 400 - 1,200 EUR/month | Medium |
| Database per tenant | Strong | 900 - 2,500 EUR/month | High |
| Dedicated cluster per enterprise | Maximum | 300-800 EUR/month/client | Very high |
In 2026, 70-80% of young B2B SaaS start with a shared schema. Moving toward more isolation is only justified by an explicit (and budgeted) enterprise requirement.
What late isolation really costs
Delaying the isolation question is tempting, but every month of debt raises the refactoring bill. Cleanly adding tenant keys and leak tests at the start costs a few days; doing it afterwards, on production data, runs into tens of thousands of euros.
| Item | Done upfront | Late refactoring |
|---|---|---|
| Tenant keys + middleware | 3-5 d (~3,000 EUR) | 15-30 d (~18,000 EUR) |
| Automated isolation tests | 2-4 d (~2,500 EUR) | 8-15 d (~10,000 EUR) |
| Production data migration | Not applicable | 10-25 d (~20,000 EUR) |
| Premium dedicated-DB option | 5-8 d (~6,000 EUR) | 12-20 d (~15,000 EUR) |
| Total | ~11,500 EUR | ~63,000 EUR |
The gap speaks for itself: what costs about 11,500 EUR done right upfront exceeds 60,000 EUR as a catch-up. That is the best argument for a clean architecture from the first screens.
Mini case study
Nadia, CTO of an HR SaaS in Singapore, is torn between a shared and a per-customer database. She has 480 SME accounts and is chasing two enterprise clients demanding strong isolation. Chosen path: shared schema for the mass (infra at 380 EUR/month) plus a dedicated-database option billed at 250 EUR/month per enterprise. Both enterprises sign: +6,000 EUR annualized MRR for an added operating cost of ~500 EUR/month. Net margin on the option: about 70%, while keeping the SME fleet's infra under 400 EUR/month.
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FAQ
Shared schema or per-tenant database to start?
Shared schema in the vast majority of cases: 150-500 EUR/month for 500 accounts versus 900-2,500 EUR per-tenant. Reserve strong isolation for enterprise clients who pay for it.
Is pooled multi-tenant secure enough for B2B?
Yes, if it relies on systematic tenant keys, isolation middleware and automated tests. The classic flaw comes from a query missing the tenant filter, not the model itself.
How much does moving to more isolation cost?
Late isolation refactoring costs 20,000-60,000 EUR depending on production data volume. Designing tenant keys upfront cuts that bill to around 11,500 EUR.
How do you serve a demanding enterprise without segregating everything?
Offer a premium dedicated-database option billed at 250-800 EUR/month per client. You keep the fleet on a shared schema while meeting occasional security requirements at high margin.
What operating budget should you plan for at 500 accounts?
Expect 150-500 EUR/month on shared schema, 400-1,200 EUR schema-per-tenant, up to 2,500 EUR database-per-tenant. Add monitoring and backups regardless of the model.
Let's scope your project. Tell us your target account count, your isolation requirements and your budget, and we will frame the most cost-effective multi-tenant architecture. 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.
