The verdict in three sentences
For a Berlin start-up selling scheduling software to retail chains, a shared database with a tenant_id column and row-level security covers 90% of what the first ten accounts need. Schema-per-tenant isolation adds 15 to 25% to the V1 budget and only pays off when prospects demand auditable logical separation. Database per tenant belongs to enterprise accounts that pay for it, because it multiplies operating and migration costs.
The three multi-tenant models compared
Multi-tenancy means one application serving several customer companies, each seeing only its own data. The decision comes before the first line of code: switching models after 30 customers often costs more than the V1 itself.
| Criterion | Shared database (tenant_id) | Schema per tenant | Database per tenant |
|---|---|---|---|
| V1 development premium | Baseline | +15 to 25% | +30 to 45% |
| Data isolation | Logical (PostgreSQL RLS) | Stronger logical | Physical |
| Hosting at 10 customers | 300 to 500 EUR/month | 400 to 700 EUR/month | 800 to 1,500 EUR/month |
| Database migrations | One | One per schema, scripted | One per database, orchestrated |
| Backup and restore of one customer | Complex (filtered export) | Simple (schema dump) | Very simple |
| Practical ceiling | Thousands of tenants | 200 to 500 tenants | 50 to 100 tenants |
| Enterprise sales argument | Weak | Medium | Strong |
For a retail chain with 20 to 150 stores, the deciding factor is rarely technical: it is the buyer's security questionnaire. German buyers in particular often ask for data residency in Germany and a documented isolation model. If two of your five priority prospects ask for it, a hybrid model (shared by default, dedicated database sold as an add-on) is the best compromise.
V1 launch budget for a B2B SaaS in Berlin
Order of magnitude for 2026 for a multi-store scheduling V1 (shift plans, absence management, payroll export, chain-level dashboard), built in 4 to 6 months by a team of 3 to 4.
| Item | Range excl. VAT | Comment |
|---|---|---|
| Discovery, wireframes, user flows | 6,000 to 12,000 EUR | 3 to 4 weeks, tested with 2 pilot customers |
| Multi-tenant core (auth, roles, isolation) | 12,000 to 22,000 EUR | The foundation you must not cut |
| Business features (scheduling, rules) | 25,000 to 55,000 EUR | The core of the value |
| Subscription billing (Stripe Billing) | 4,000 to 8,000 EUR | Plans, trials, invoices |
| SAML SSO and SCIM provisioning | 6,000 to 12,000 EUR | Often required above 200 employees |
| QA, security, go-live | 7,000 to 11,000 EUR | Load tests and code review |
| V1 total | 60,000 to 120,000 EUR | Excluding hosting and maintenance |
SAML SSO can move to V1.1 if your first customers have fewer than 100 employees, saving 6,000 to 12,000 EUR at launch. Data isolation and role management cannot wait: they are the first things an IT department checks. Works council (Betriebsrat) involvement in scheduling tools also means audit logs of who changed which shift should be in the V1.
Operations: what costs money after go-live
Hosting grows with your customer base: 300 EUR per month for 10 accounts on a shared database, up to 1,500 EUR per month for 40 accounts with dedicated databases and staging environments, typically on Hetzner, IONOS or AWS Frankfurt. Add monitoring (Sentry, Grafana) at 50 to 200 EUR per month plus ongoing maintenance. At Kolonell, application maintenance runs at 35,000, 75,000 or 120,000 FCFA per month (53, 114 or 183 EUR) depending on service level; new features are quoted separately. See our approach to custom web applications.
Mini case study
Lena, co-founder of a scheduling start-up in Berlin, targets chains of 30 to 80 stores at 450 EUR per month per chain. She weighs a shared database (V1 at 78,000 EUR) against schema per tenant (V1 at 94,000 EUR, i.e. +20%).
Need a professional website?
Kolonell builds websites that attract clients, optimized for the Sénégalese market. Free quote in 2 minutes.
Over 24 months with 25 customers: recurring revenue of roughly 25 x 450 x 12 = 135,000 EUR in year two. The 16,000 EUR gap equals 3.5 months of that year's revenue. Hosting: 450 EUR per month shared versus 650 EUR with schemas, a 4,800 EUR gap over two years. Lena picks the shared database with RLS, documents isolation in a security white paper and offers a dedicated database option at 150 EUR more per month. Two of her first ten customers take it, which covers their hosting cost from month three.
FAQ
Is row-level security (RLS) enough for a demanding buyer?
In most cases yes, provided it is tested automatically: a suite of 50 to 100 tests proving that one tenant never reads another's data. Attach the results to your security questionnaire answers.
How long does a sellable multi-tenant V1 take?
Plan 4 to 6 months, including 3 to 4 weeks of discovery. A V1 shipped in under 3 months almost always sacrifices roles, audit logs or billing.
Do we need SAML SSO at launch?
Only if your prospects exceed 200 employees or systematically use Entra ID or Okta. The budget is 6,000 to 12,000 EUR, often recovered with the first mid-sized account.
Can we move from a shared database to dedicated databases later?
Yes, if tenant_id exists in every table from day one. Moving one customer to a dedicated database then takes 2 to 5 days, versus several weeks if the architecture did not plan for it.
Where should a German start-up host?
An EU provider with data in Germany (Hetzner, IONOS, AWS Frankfurt) reassures retail buyers and simplifies GDPR answers. Budget 300 to 1,500 EUR per month depending on volume.
Let's scope your project. We define your multi-tenant architecture, V1 scope and a 4 to 6 month delivery plan before you sign your first accounts. 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.
