The verdict in three sentences
Taking over an existing application costs on average 30 to 60 % of a fresh build — but only if a prior audit has measured the technical debt. That code audit (3,000 to 10,000 EUR, 1 to 3 weeks) is non-negotiable: without it, you're buying an invisible liability. Missing documentation and debt (20 to 40 % of the rebuild cost) are the two main traps.
The cost of a takeover audit
Before taking over, you must know what you're taking over. Here are 2026 orders of magnitude by application size.
| Application size | Audit (EUR) | Audit lead time | Deliverables |
|---|---|---|---|
| Small (MVP, <15k lines) | 3,000-4,500 | 1 week | Report + major risks |
| Medium (15-50k lines) | 4,500-7,000 | 1-2 weeks | Report + debt + plan |
| Large (>50k lines) | 7,000-10,000 | 2-3 weeks | Full audit + roadmap |
| Critical (payment, data) | +2,000-3,500 | +1 week | Dedicated security audit |
The audit delivers a technical-debt report, a risk map, and a costed remediation plan. It's your insurance before committing the takeover budget.
Takeover cost vs fresh build
Takeover isn't always cheaper: it all depends on the debt. Let's compare on a medium app whose fresh build would cost 60,000 EUR.
| State of inherited code | Technical debt | Takeover cost | vs fresh (60,000 EUR) |
|---|---|---|---|
| Clean, documented | 10-15 % | 18,000-24,000 EUR | 30-40 % |
| Decent, lightly documented | 20-30 % | 27,000-33,000 EUR | 45-55 % |
| Degraded, undocumented | 30-40 % | 33,000-42,000 EUR | 55-70 % |
| Critical / abandoned | 40 %+ | Rebuild often advised | 80-100 % |
Beyond 40 % debt, taking over costs almost as much as rebuilding: the audit exists precisely to decide between takeover and rebuild.
Mini case study
Mehdi, director of an e-commerce SME in Marseille, inherited an app abandoned by his former vendor. Full-rebuild quote: 60,000 EUR. He first orders an audit at 5,500 EUR over 2 weeks. Verdict: decent but lightly documented code, debt at 25 %. Costed takeover: 30,000 EUR (50 % of a fresh build). Savings versus rebuild: 24,500 EUR after the audit. He approves a 3-sprint remediation plan and recovers his project in 9 weeks instead of starting from scratch.
Need a professional website?
Kolonell builds websites that attract clients, optimized for the Sénégalese market. Free quote in 2 minutes.
FAQ
Why pay for an audit before takeover?
Because it quantifies invisible risk. A 5,000 EUR audit can save you from committing 30,000 EUR on unrecoverable code — or confirm that a takeover at 50 % of a fresh build is feasible. It's the best decision-to-cost ratio in the project.
What happens if documentation is missing?
The vendor rebuilds a map through reverse engineering, adding 15 to 25 % to the takeover cost. Then require delivered documentation so you never relive this situation.
How do you know whether to take over or rebuild?
The rule: beyond 40 % technical debt, a rebuild becomes more cost-effective. Below that, takeover at 30-60 % of a fresh build is almost always the right call. The audit decides with numbers.
Can you keep existing data?
Yes, a data migration is generally possible and budgeted separately (2,000 to 6,000 EUR depending on volume). The audit checks data integrity and structure before takeover.
How long to take over a project?
Expect 1 to 3 weeks of audit then 6 to 12 weeks of remediation depending on size. A sprint-based plan lets you re-deploy gradually, without a risky big-bang.
Let's scope your project. Send us repo access or a description of the app to take over: we'll price the audit then the remediation plan. 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.
