The verdict in three sentences
A WinDev desktop application that has run invoicing, stock and orders for 15 years is an asset, but it becomes a major risk the day the only developer who knows it retires. The right method is almost never a big-bang rewrite: it is a progressive, module-by-module migration over 6 to 12 months, preceded by a 2 to 4 week audit that maps the screens, the hidden business rules and the HFSQL database. Cost depends less on the number of screens than on the number of undocumented business rules.
Why the status quo costs more than it seems
IT managers at distribution SMEs across Europe, Quebec or French-speaking Africa know the scenario: 180 screens, a 40 GB HFSQL database, mandatory Windows workstations, remote access patched together with remote desktop, and a freelance developer announcing his departure in 18 months. Here are the risks with 2026 orders of magnitude.
| Status quo risk | Probability over 3 years | Estimated impact |
|---|---|---|
| Developer leaves without handover | High | 2 to 6 months with no changes possible |
| HFSQL failure with no tested recovery | Medium | 3 to 10 days without invoicing |
| Incompatibility with a Windows update | Medium | 1 to 5 days down on part of the workstations |
| Unable to open a customer portal or API | Certain | Lost online orders, 5 to 15% of potential revenue |
| WinDev licences and workstations to maintain | Certain | 3,000 to 8,000 EUR a year |
| Hard to hire a WinDev profile | High | Day rate of 500 to 700 EUR, scarce |
The last point is often decisive: in 2026 a React, Next.js or Node developer is ten times easier to hire than a WinDev specialist, especially outside France.
Full rewrite or module-by-module migration
| Criterion | Full rewrite | Progressive module migration |
|---|---|---|
| Market budget (180 screens) | 60,000 to 200,000 EUR in one go | Same order of magnitude, spread over 6 to 12 months |
| Go-live | Single cutover, high risk | Module by module, rollback possible |
| Double entry during transition | None, but everything switches on one day | Avoided through sync between HFSQL and the new database |
| First visible benefits | After 9 to 15 months | From the first module, at 2 or 3 months |
| Risk of missing a business rule | High | Reduced, each module is tested against the legacy |
| Burden on users | Massive one-off training | Training per department, 2 to 4 hours per module |
At Kolonell, each module is priced on the custom application grid: simple 2,500,000 to 4,000,000 FCFA (3,810 to 6,100 EUR), medium 4,000,000 to 7,000,000 FCFA (6,100 to 10,670 EUR), complex 7,000,000 to 15,000,000+ FCFA (10,670 to 22,870+ EUR). The full programme, the audit and data synchronisation are quoted separately once the mapping is complete.
The method in five steps
| Step | Duration | Deliverable |
|---|---|---|
| Audit and mapping | 2 to 4 weeks | Inventory of the 180 screens, business rules and HFSQL schema |
| Technical foundation | 3 to 5 weeks | Authentication, permissions, PostgreSQL database, sync with HFSQL |
| Module 1, the most used (often orders) | 6 to 10 weeks | Web screens, tests on real data, training |
| Following modules (stock, invoicing, purchasing) | 4 to 8 weeks each | Cutover department by department |
| Decommissioning WinDev | 2 to 4 weeks | HFSQL archived read-only, licences stopped |
The key is two-way synchronisation during the transition: departments still on WinDev and those already on the web see the same data. It takes work upfront, but it removes double entry and the stress of a single cutover.
One more tip: have the original developer review the WinDev code during the audit, even for a few paid days at 500 to 700 EUR. Every rule he explains saves a week of investigation later.
Mini case study
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Isabelle, IT manager at an electrical supplies distributor near Montreal with 65 staff and 14 M EUR in revenue (about 20 M CAD), splits her 180 screens into 5 modules. Orders and invoicing are complex, stock and purchasing are medium, the customer portal is simple.
Taking the top of each Kolonell range: 2 complex modules at 22,870 EUR, 2 medium modules at 10,670 EUR and 1 simple module at 6,100 EUR, she gets 73,180 EUR of module development, excluding the audit and synchronisation, which are quoted separately. On the savings side, she drops 6,000 EUR a year in licences and workstation upkeep, and her customer portal targets 4% more orders, about 560,000 EUR of potential revenue. She adds maintenance at 75,000 FCFA a month (114 EUR), i.e. 1,368 EUR a year.
FAQ
Can WinDev code be converted automatically to web code?
Conversion tools exist but produce code that is hard to maintain and carry over the legacy's flaws. On 180 screens, automatic conversion rarely covers more than 40 to 60% of the need without heavy rework.
What happens to the 40 GB HFSQL database?
It is migrated to PostgreSQL table by table, with control scripts comparing totals. History can stay available read-only for 10 years to meet accounting obligations.
How long do users work on two tools?
With a module migration, each department switches only once, after 2 to 4 hours of training. Company-wide, both systems coexist for 6 to 12 months, without double entry.
Should we keep the original developer during the migration?
It is strongly advised, even part time: 5 to 10 days over the whole project is often enough. He validates business rules and speeds up the audit.
How long until the first module is in production?
Allow 3 to 4 months after the audit starts: 2 to 4 weeks of audit, 3 to 5 weeks of foundation, then 6 to 10 weeks for the first module.
Let's scope your project. We start with an audit of your WinDev application to split the modules, set the cutover order and a 6 to 12 month schedule. 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.
