Solution
Legacy Application Modernization
We modernise systems the business depends on by replacing them capability by capability, so value arrives early and the risk of a single catastrophic cutover never exists.
How do you modernise a legacy system without a rewrite?
By routing traffic through a facade and replacing capabilities behind it one at a time — the strangler pattern. New functionality is built in the modern system, the facade decides which system handles each request, and the legacy application shrinks until it can be switched off. Each step is independently deliverable and independently reversible.
The alternative — building a complete replacement and switching over in one event — concentrates all risk at a single moment, typically after the budget is spent and while the business has been asked to freeze changes for a year.
Who this is for
Where this fits.
- Organisations running business-critical software on unsupported technology
- Teams whose delivery has slowed because the codebase resists change
- Businesses facing an end-of-life platform, framework or hosting arrangement
Challenges
What tends to be in the way.
The system works and nobody understands it
Behaviour is encoded in a codebase with no tests and no documentation, and the people who wrote it have left.
Business rules that exist only in code
Years of undocumented edge cases are embedded in the application, and losing them would break real processes.
A rewrite that was attempted before
A previous replacement project ran long, delivered nothing usable and ended the organisation’s appetite for another.
Every other system depends on it
Integrations, reports and scheduled jobs all point at the legacy application, so it cannot simply be replaced.
Our approach
How we run it.
Map behaviour before changing it
Capabilities, data flows, integrations and business rules documented from the running system, not from old specifications.
Put a facade in front
A routing layer that can direct each request to the legacy system or its replacement, making the transition invisible to consumers.
Replace by capability
The highest-value, lowest-risk capability moves first, proving the pattern before anything critical follows.
Run both and reconcile
Where correctness is critical, both systems process the same input and outputs are compared before the old path is retired.
Decommission deliberately
The legacy system is retired only once nothing depends on it, with data archived in a readable, queryable form.
Outcomes
What you are left with.
Deliverables and capability, described as what exists at the end rather than as business results we cannot verify.
- Improvements delivered continuously rather than at the end
- A rollback path available at every stage
- Business rules preserved because they were captured, not guessed
- A supported, changeable platform with the knowledge documented
Considering legacy application modernization?
Tell us where you are now and what is blocking progress. We will come back with a sequence.