Answers
How do you modernise a legacy system?
In short
Modernise a legacy system using the strangler pattern: build the new at the edge, route traffic progressively, prove parity, and retire the old code only when nothing depends on it.
Short answer
Modernise a legacy system using the strangler pattern: build the new at the edge, route traffic progressively, prove parity, and retire the old code only when nothing depends on it.
What this actually means in practice
Avoid the big-bang rewrite. Slice by business capability; route at the API or message layer; instrument everything so you can prove the new behaviour matches the old. Treat the legacy system as a product to be retired, not a project to be replaced.
The most common pitfall
Trying to replace everything in one cutover and discovering the dependencies you didn't map.
What to do next
Pick the smallest bounded slice with measurable success criteria and ship it.
Frequently asked questions
Does Forth Systems help with this?
Yes — Forth Systems works with banks, payment institutions, insurers and infrastructure operators on exactly this kind of work. Engagements start with a fixed-scope assessment so you see the shape before committing.
How experienced is the team?
Engagements are staffed by named, UK-based senior engineers — not a rotating offshore pool. References from the second line of comparable clients are available on request.
Where are you based?
Edinburgh-based, delivering UK-wide with onsite presence in London and across Scotland as required.
How fast can we start?
Most engagements start within 2-4 weeks of a signed SoW, faster where an existing supplier framework is in place.