The verdict in three sentences
A client portal + document-collection MVP costs between 28,000 and 55,000 € in 2026, while a full platform (production, DMS, follow-up, billing) runs 70,000 to 140,000 €. Add 12 to 18 % annual maintenance and a 12 to 20 week timeline at a French day rate of 450 to 650 €. Custom becomes profitable once manual entry and per-user subscriptions outweigh amortizing the build over five years.
What the development really costs
The price depends on scope and how deeply the tool integrates with your existing production software. Here are the ranges seen on the French market in 2026.
| Scope | Key features | 2026 cost (€) | Timeline |
|---|---|---|---|
| Portal MVP | Document collection, DMS vault, notifications | 28,000 – 55,000 | 12–14 wks |
| Intermediate | + auto follow-up, production tracking, dashboard | 55,000 – 90,000 | 14–18 wks |
| Full platform | + billing, review workflow, Cegid/bank APIs | 70,000 – 140,000 | 16–20 wks |
| Annual maintenance | Fixes, evolutions, EU hosting | 12–18 % of build | Recurring |
| Average day rate | Senior fullstack dev, France | 450 – 650 € | — |
Maintenance is not optional: budget 10,000 to 20,000 € per year for a mid-sized firm, covering regulatory updates, security and two to four evolutions annually.
Custom vs SaaS subscription: the 5-year math
A Pennylane- or ACD-style subscription billed at 25 to 60 € per user per month quickly becomes a heavy recurring cost. For 20 staff at an average of 45 €, you reach roughly 10,800 € per year, or 54,000 € over five years, without owning the asset.
| Line item | SaaS 20 users (5 yrs) | Custom (5 yrs) |
|---|---|---|
| Subscription / license | 54,000 € | 0 € |
| Initial build | 0 € | 90,000 € |
| Maintenance / evolutions | partly included | 60,000 € |
| Add-on modules | 8,000 – 15,000 € | included |
| Asset owned at end | No | Yes |
| Order-of-magnitude total | 62,000 – 69,000 € | 150,000 € |
Custom costs more in cash but removes the per-user tax: above 25 staff or with atypical workflows, the gap narrows sharply and the asset stays on your balance sheet.
Mini case study
Claire runs a 22-person accounting firm in Nantes. Her assistants spend an average of 6 hours per week each chasing clients for documents. An 80,000 € custom portal automates collection and cuts that time by 40 %, i.e. 2.4 h × 22 = 52.8 hours saved per week. At a loaded cost of 28 €/h, that is 1,478 € per week, about 68,000 € per year. The portal pays for itself in under 18 months, maintenance included.
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FAQ
What is the cheapest MVP that still adds value?
A document-collection portal with a DMS vault starts at 28,000 € and ships in 12 to 14 weeks. It is the best entry point to test adoption before investing further.
Is maintenance really essential?
Yes. Without it the software degrades: security holes, browser incompatibilities, unfollowed regulatory changes. Budget 12 to 18 % of the build cost per year.
At how many users does custom beat SaaS?
The tipping point is usually around 25 users, or as soon as you need integrations the SaaS bills as add-ons. Below that, a vertical SaaS is often cheaper.
Can it connect to Cegid or banks?
Yes, via API and bank aggregation (PSD2). Budget 8,000 to 20,000 € depending on the number of connectors, planned from the spec stage.
Where should client data be hosted?
On EU infrastructure such as OVHcloud or Scaleway for GDPR compliance. Managed hosting runs 1,200 to 3,600 € per year for a mid-sized firm.
Let's scope your project. Tell us your scope (headcount, current tools, indicative budget between 30,000 and 140,000 €) and target timeline. 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.
