The verdict in three sentences
A Delphi application running since 2004 whose developer has retired is an operational risk, not just technical debt. Rewriting it as a web app costs EUR 50,000 to 120,000 for a distribution SME, split into 3 to 4 phases over 6 to 10 months, without stopping invoicing or shipping. The real danger lies in undocumented business rules: customer discounts, free-shipping thresholds, VAT exceptions that nobody can explain anymore.
Why rewrite now rather than wait for a failure
The warning signs are well known: a Windows machine that can no longer be updated, a Paradox or Firebird database with no tested backup, no remote working, no access for field sales reps around Brandenburg. Every month that passes raises the cost of migration, because the people who know the exceptions are leaving too.
| Option (2026 estimate) | Initial cost | Timeline | Main risk |
|---|---|---|---|
| Status quo + freelance Delphi support | EUR 6,000 to 12,000/year | Immediate | Nobody left for urgent fixes |
| Emulation (Citrix, RDP) | EUR 8,000 to 15,000 | 1 month | Technical debt moved, not solved |
| Standard ERP | EUR 40,000 to 90,000 + EUR 150/user/month | 6 to 12 months | Imposed processes, loss of specifics |
| Phased web rewrite | EUR 50,000 to 120,000 | 6 to 10 months | Forgotten business rules |
| Big-bang rewrite | EUR 60,000 to 130,000 | 8 to 12 months | Business stoppage if cutover fails |
Splitting the rewrite into phases
The lowest-risk method runs old and new systems side by side. The web app takes over one scope, the database is synchronised, then the matching Delphi module is switched off.
| Phase | Scope | Indicative budget | Duration |
|---|---|---|---|
| 0. Audit and reverse engineering | Code reading, rule inventory, database mapping | EUR 6,000 to 12,000 | 3 to 4 weeks |
| 1. Master data and customers | Items, prices, terms, customer accounts | EUR 12,000 to 25,000 | 6 to 8 weeks |
| 2. Orders and stock | Order entry, picking, reservations, stock counts | EUR 15,000 to 35,000 | 8 to 10 weeks |
| 3. Invoicing and accounting | Invoices, credit notes, accounting export, e-invoicing | EUR 12,000 to 30,000 | 6 to 8 weeks |
| 4. Reporting and mobile access | Dashboards, sales rep app | EUR 5,000 to 18,000 | 4 to 6 weeks |
| Migration of 15 years of data | Cleaning, deduplication, checks | Included, 8 to 15 days | In parallel |
Phase 3 is timely in 2026: in Germany, all businesses must already be able to receive e-invoices (XRechnung, ZUGFeRD) since 2025, and issuing becomes mandatory for most SMEs by 2027 to 2028. Your Delphi app will not handle it. After go-live, maintenance runs at EUR 1,200 to 2,500 per month.
Funding the project
Depending on your situation, several levers exist: state-level digitisation programmes such as Berlin's digital grants, KfW loans for digital projects, and federal SME support schemes. These often cover 20 to 50% of eligible costs, with caps and deadlines to check at the time of application. The file requires a specification and a detailed quote, which the phase 0 audit produces.
Mini case study
Thomas, managing director of an industrial supplies distributor in Berlin (32 staff, 9 app users), currently pays EUR 9,000/year to a Delphi freelancer and loses about 3 hours per week per sales rep (4 reps) re-keying orders for lack of mobile access. He prices the rewrite at EUR 84,000 and obtains a 30% grant, leaving EUR 58,800 to fund. Annual gains: 624 hours of re-keying valued at EUR 40, so EUR 24,960, plus the end of freelance support. With maintenance at EUR 1,500/month (EUR 18,000/year), the net gain is about EUR 15,960/year, plus operational security. Payback in about 3 years and 8 months, excluding the cost of an avoided outage.
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FAQ
Can we reuse the existing Delphi code?
The code serves as documentation, not as a rewrite base. The 3 to 4 week audit extracts the business rules, usually 150 to 400 rules for a distribution app.
Do we need to stop operations during cutover?
No, with a phased rewrite each cutover happens over a weekend with rollback possible. Plan for 2 days of double entry at most per phase.
How much does migrating 15 years of data cost?
It is included in the budget and takes 8 to 15 days of work. Expect 5 to 15% duplicate customers or items to clean up.
Why not buy an ERP?
An ERP fits if your processes are standard. At EUR 150 per user per month, 9 users cost EUR 16,200/year, with no guarantee you keep your specific discounts.
Which technology for the new app?
Kolonell uses a standard, documented web stack (TypeScript, PostgreSQL) that any provider can take over. That is the main lesson of the Delphi case.
Let's scope your project. Describe your current app, number of users and critical modules: we will price the audit, the phases and an indicative budget of EUR 50,000 to 120,000 over 6 to 10 months. Detailed quote within 48 h via our quote form. 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.
