The verdict in three sentences
For a Dublin SME whose business application dates from 2012, a progressive rebuild (strangler pattern) is almost always safer than a full rewrite: you replace the application screen by screen while it keeps running. Budget an audit at EUR 3,000 to 6,000, then EUR 40,000 to 120,000 for 30 to 80 screens, over 6 to 12 months. The status quo is not free: an unpatched PHP version and a single developer who knows the code form an operational risk that your insurer and your customers will eventually bill you for.
Why your 2012 application is already expensive
Many SME IT leads see modernization as a new expense. In reality the cost is already there, just scattered: hours lost on slow screens, untracked incidents, changes refused because "nobody dares touch that module". PHP 5.6 and 7.x no longer receive security fixes, and the in-house frameworks of the time (or Zend Framework 1, Symfony 2) block any upgrade.
| Status quo cost item (2026 order of magnitude) | Estimated annual cost | Comment |
|---|---|---|
| Dependence on a single developer | EUR 15,000 to 40,000 of risk | Departure or sick leave = frozen roadmap |
| Downtime (2 to 5 days a year) | EUR 8,000 to 25,000 | Manual entry, delayed invoicing |
| Known unpatched vulnerabilities | Average SME incident: EUR 20,000 to 60,000 | Ransomware, data leak, GDPR notification |
| Slow screens (10 min lost per user per day) | EUR 9,000 for 15 users | Based on EUR 35 loaded hourly cost |
| Refused or patched-up changes | Hard to quantify | Loss of commercial competitiveness |
| Hosting on an ageing server | EUR 2,000 to 6,000 | No tested backup, no monitoring |
Added up, an SME with 15 to 30 users often carries EUR 30,000 to 80,000 a year in hidden costs. That is the figure to put next to the modernization quote.
Full rewrite vs progressive rebuild: the comparison
A full rewrite is tempting: blank page, modern stack, single delivery. Yet it often fails, because the old application holds undocumented business rules that are rediscovered too late. The strangler pattern places an API layer in front of the existing system, then rebuilds in React (with a recent Node.js or Laravel back end) one domain at a time: quotes, then orders, then stock.
| Criterion | Full rewrite | Progressive rebuild (strangler) |
|---|---|---|
| Budget, 30 screens | EUR 45,000 to 70,000 | EUR 40,000 to 60,000 |
| Budget, 80 screens | EUR 110,000 to 160,000 | EUR 90,000 to 120,000 |
| Time to first visible gain | 6 to 9 months | 6 to 8 weeks |
| Business regression risk | High (single cutover) | Low (cutover per module) |
| Dual maintenance during project | Yes, for the whole duration | Limited to the current module |
| Option to stop midway | No, investment lost | Yes, each delivered module stays useful |
| User training | All at once, big shock | Gradual, smoother adoption |
The typical method runs in four stages: code and data audit (2 to 4 weeks), shared API and authentication layer, module-by-module migration with automated tests, then decommissioning of the old code. The audit delivers a screen map, a technical debt score and a per-module estimate, so you can prioritize by business value.
Mini case study
Siobhan, IT lead at a building materials distributor in Dublin (28 users), runs a 2012 PHP application with 52 screens. Estimated hidden costs: EUR 14,000 of slowness, EUR 12,000 of downtime and a dependence risk she values at EUR 20,000 a year, i.e. EUR 46,000 a year.
Selected quote: audit EUR 4,500, then a progressive rebuild in 5 lots for EUR 78,000 over 9 months, i.e. EUR 82,500. From the second lot (quotes and orders, month 3), slowness disappears for 60% of usage. With savings ramping up over the year, payback lands around 22 months, and the company no longer hangs on a single developer.
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FAQ
How much does a legacy PHP application audit cost in Dublin in 2026?
Budget EUR 3,000 to 6,000 for a 30 to 80 screen application, delivered in 2 to 4 weeks. It covers code, dependencies and database analysis plus a module-by-module estimate.
Can we keep the existing database?
Yes, in 70 to 80% of cases the MySQL database is kept and cleaned up progressively. Indexes, constraints and versioned migrations are added without interrupting operations.
Why React rather than a simple PHP upgrade?
A PHP upgrade alone costs EUR 15,000 to 35,000 but fixes neither usability nor dependence on old code. React with a clean API eases hiring, mobile access and future integrations.
Will my users have to switch tools overnight?
No. With the strangler pattern each module switches separately, often every 6 to 8 weeks. Users move between old and new screens with a single sign-on.
What happens after the rebuild?
A maintenance contract at EUR 1,000 to 3,000 a month covers fixes, security updates and small changes. It also guarantees up-to-date documentation, the basis of your independence.
Let's scope your project. Send us your screen count, PHP version and priority modules: we will price the audit and a lot-by-lot rebuild plan with an indicative budget and 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.
