Legacy system modernisation

An old system is rarely a bad system. It usually holds years of business rules nobody can reconstruct from memory any more. The real problem is that it has become expensive to change and risky to operate.

A full rewrite is the last option

"Rewrite everything from scratch" projects fail in most cases because they try to reproduce, in two years, behaviour accumulated over ten. We prefer incremental modernisation: isolate components, replace them one at a time, and keep the system running throughout.

How we proceed

We start with a two-week technical audit: we review the code, the database, the dependencies, the release process and the incidents of the last year. The output is a risk map and a staged modernisation plan, each stage with a measurable benefit.

Then we install a safety net: characterisation tests over current behaviour, an automated delivery pipeline and monitoring. Only then do we start changing code, because only then can we prove that nothing broke.

Typical results

Release time reduced from weeks to hours, a significant drop in production incidents and a predictable maintenance cost.

Included deliverables

How we work