Fictional example
Example: Legacy Check of a Delphi inventory management system
An inventory management system in Delphi 7, a developer close to retirement and mandatory e-invoicing around the corner: this fictional example shows how a Legacy Check assesses such a situation – and which path leads out of it. You can download both parts of the report as PDFs.
The situation
Muster Haustechnik Großhandel GmbH (fictional) – Wholesaler of plumbing and heating supplies with 85 employees, a central warehouse and two trade counters.
Complete inventory management and ERP: article and price maintenance for about 1.4 million articles, quotes, orders, delivery notes and invoices, purchasing, warehouse and picking, and project business with project prices for installer firms.
MERKUR has been developed since 1998 by a one-person software company and is still maintained by the same developer. He has announced that he will retire at the end of 2027; the rights to the source code were transferred by contract in 2025. At the same time, mandatory e-invoicing is around the corner, and the installer customers expect digital ordering. Management wanted to know whether MERKUR has a future – and if not, how to switch without disrupting day-to-day business.
- Assess MERKUR's future and the risks for operations
- Meet the e-invoicing obligation in time
- Secure the developer's knowledge while he is still available
Scope of the Legacy Check
Fixed price €2,499 net · Completed within 2 calendar weeks
- Analysis of the complete source code and database schema (anonymised copy, no live data)
- AI-assisted code analysis with the right model for each task and proven prompts, all findings reviewed by experienced developers
- Two interviews: business department (sales and warehouse) and the current developer
- Review of infrastructure, operations, third-party components and licences
- Results presentation (online, 60 minutes) and this report
The result
Strong for the business, technically at the end of its life cycle
MERKUR maps Muster Haustechnik's business in great depth – pricing logic and project business are real strengths. The technical foundation, however, is exhausted: Delphi 7 and Firebird 2.5 are no longer developed, and all knowledge sits with one developer who retires at the end of 2027. Two issues cannot wait: the database reachable from the internet and mandatory e-invoicing from 1 January 2027. After that, we recommend replacing MERKUR step by step with a web application.
Traffic-light rating
The five biggest risks
| No. | Risk | Rating | Action |
|---|---|---|---|
| R1 | E-invoicing obligation from 2027 cannot be metMERKUR creates invoices only as PDFs. From 2027 the company (prior-year turnover above €800,000) must issue invoices to domestic business customers as e-invoices. | Critical | E-invoicing service (XRechnung, ZUGFeRD) next to MERKUR – ready by 31 December 2026. |
| R2 | Database reachable from the internetFor the nightly shop sync, the Firebird port is open in the firewall; access is unencrypted and uses SYSDBA. | Critical | Close the port immediately, sync through a secured interface, accounts with minimal rights. |
| R3 | Knowledge monopoly with an expiry dateAll technical knowledge sits with one external developer who retires at the end of 2027. | High | Agree a knowledge transfer by contract, document the business rules. |
| R4 | Platform without a futureDelphi 7, Firebird 2.5 and key components are no longer maintained; Windows Server 2016 loses support in January 2027. | High | Short term Firebird 5 and Windows Server 2025, medium term replacement. |
| R5 | No source code managementSource code and compiler licence are on the developer's computer; versions are stored as ZIP archives. | High | Git and build environment in the company, licences in the company's name. |
The options compared
| Option | Effort without AI | Duration without AI | Saving with AI | Assessment |
|---|---|---|---|---|
| ASecure and meet obligationsE-invoicing service, shield the database, Firebird 5 and Windows Server 2025, Git and build in-house; MERKUR itself stays unchanged. | 55–70 PD | 3–4 months | 30–40% | Essential and immediate |
| BUpgrade to current DelphiCurrent Delphi version with Unicode and 64-bit, replacement of discontinued components; user interface and processes stay the same. | 470–630 PD | 18–24 months | 50–70% | Feasible, but does not solve the skills shortage |
| CStep-by-step replacement with a web applicationrecommendedNew application with ASP.NET Core (C#), Angular and PostgreSQL, module by module using the strangler fig pattern; MERKUR runs in parallel until the last module has been taken over. | 840–1,080 PD | 36–42 months | 50–60% | Recommended (after option A) |
| DIndustry software for wholesalersIntroduction of a standard inventory management system for plumbing and heating wholesalers, with customisation. | high (plus licences) | 15–23 months | approx. 20% | Secondary – high customisation needs |
Effort and duration estimated without AI. Our AI-assisted development reduces time and cost by the range shown; the roadmap already includes AI.
Recommendation and roadmap
We recommend handling the obligations and critical risks immediately (option A), then replacing MERKUR step by step with a web application (option C). The e-invoicing service comes first, built as part of the new architecture. Securing the developer's knowledge while he is available is crucial.
- Phase 1
Obligations and security
Months 1–3 · 35–45 PD
E-invoicing service by 31 December 2026, shield the database, Firebird 5 and Windows Server 2025, Git and build in-house
- Phase 2
Knowledge and foundation
Months 3–6 · 60–80 PD
Document business rules with the developer, interface layer (API) on top of the database, test cases from real documents
- Phase 3
Modular replacement
Months 6–20 · 280–350 PD
Master data and prices, sales, purchasing, warehouse with mobile data capture in the browser
- Phase 4
Migration and shutdown
Months 20–24 · 40–55 PD
Move to PostgreSQL, end parallel operation, archive and switch off MERKUR
All four phases: 415–530 PD over approx. 24 months with AI – approx. 895–1,150 PD without AI. Accuracy ±25%. Phase 1 must be completed by 31 December 2026.
Download the report
The report has two parts: a compact summary for management and a detailed analysis for IT. Click a page to enlarge it.
Part 1: Management summary
Download PDF
Part 2: Detailed analysis
Download PDF
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Your own Legacy Check
Fixed price €2,499 net, results usually within two weeks – with a report, a results presentation and a concrete recommendation for your application.