The verdict in three sentences
A custom web application costs between €25,000 (simple MVP) and €400,000 (complex platform) in 2026, with development alone accounting for ~55% of the budget. The real price driver is not the number of screens but business complexity: rules, third-party integrations and the required QA level. Budget 15 to 20% of the build per year for maintenance to keep the app alive and secure.
2026 price ranges by type
The figures below are 2026 orders of magnitude for a French agency (day rate €550-750), with scope frozen after discovery.
| Type | Budget (ex-VAT) | Timeline | Typical team |
|---|---|---|---|
| Simple MVP (1 flow) | €25,000-45,000 | 2-4 months | 1 dev + part-time design |
| Standard business app | €60,000-120,000 | 4-6 months | 2 devs + PO + UX |
| Advanced business app | €120,000-180,000 | 6-9 months | 3 devs + QA + PO + UX |
| Complex platform | €150,000-400,000 | 9-14 months | Squad of 5-7 |
| Legacy rebuild | €80,000-250,000 | 5-10 months | Depends on tech debt |
An MVP doesn't mean "cut corners": it means one critical flow delivered cleanly. Each extra flow (back office, mobile app, admin area) mechanically adds 20 to 40% to the budget.
Where the money actually goes
Breakdown of a typical €100,000 project. Understanding this structure helps you challenge a quote line by line.
| Item | Share | Amount | What it covers |
|---|---|---|---|
| Discovery & specs | 10% | €10,000 | Workshops, backlog, wireframes |
| UX / UI design | 15% | €15,000 | Design system, high-fidelity screens |
| Development | 55% | €55,000 | Front, back, database, API |
| QA & acceptance | 10% | €10,000 | Testing, bug fixing, e2e tests |
| Deployment & go-live | 10% | €10,000 | CI/CD, infra, production release |
Beware a quote where discovery is €0: the cost always resurfaces later, as change requests, when vague specs blow up mid-development.
Recommended billing milestones
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Breaking the project into lots protects both parties and paces cash flow.
| Milestone | Deliverable | % of budget |
|---|---|---|
| Kick-off | Signature + validated backlog | 20% |
| End of discovery/design | Mockups + frozen specs | 20% |
| Dev sprint 1 | Demonstrable core flow | 25% |
| Dev sprint 2 | Full feature set | 20% |
| Acceptance + go-live | App in production | 15% |
Mini case study
Nicolas, IT director of an industrial SME in Paris, needs to replace an Excel-based production tracker. Scope: a standard business app, 5 screens, connection to the existing ERP. Selected quote: €95,000, 5-month timeline. Split: €9,500 discovery, €14,250 design, €52,250 dev, €9,500 QA, €9,500 deployment. Annual maintenance at 18% = €17,100/year. Estimated gain: 12 hrs/week of re-keying avoided across 4 roles, i.e. ~2,000 hrs/year at €35/hr = €70,000/year of recovered value. ROI reached by month 18, maintenance included.
FAQ
Why do two agencies quote double the price of each other? Because scope isn't framed the same way: one quotes the strict MVP (€35,000), the other includes back office, mobile and integrations (€85,000). Always compare on identical scope.
Fixed price or time-and-materials? Fixed price reassures on a frozen scope (MVP); T&M (day rate €550-750 in Paris) suits evolving products. In practice, fixed price for the MVP then T&M to iterate is the healthiest combo.
How much is maintenance? Budget 15 to 20% of the build per year: fixes, security updates, version upgrades, small enhancements. On a €100,000 build, that's €15,000-20,000/year.
Can you cut the budget without sacrificing quality? Yes: narrow the scope to the critical flow, reuse an existing design system, pick proven open-source building blocks over full custom. You can often save 20-30% without touching robustness.
How long until production? From 2-4 months for an MVP to 9-14 months for a complex platform. Discovery (3-4 weeks) is the best investment to hit that timeline.
Let's scope your project. Tell us your critical flow, indicative budget and deadline, and we'll tell you which tier you fall into. 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.
