Assessment and migration strategy
Dependency mapping, risk register, sequencing by business value and a costed plan you can take to a board, produced in weeks rather than quarters.
Enterprise Legacy Migration
Enterprise Legacy Migration
Legacy system modernization in slices, with no cutover weekend.
What this engagement actually is
We move monoliths, mainframe-era systems and end-of-life platforms onto modern foundations while they keep serving production traffic. The pattern is a routing seam, incremental extraction and staged data ownership - never a big-bang rewrite that has to land perfectly on a Sunday night.
What you end up with
- Production traffic migrated incrementally, with rollback at every step
- No cutover weekend and no feature freeze
- A decommissioning date the finance team can plan against
- Documentation and tests for behaviour that previously lived in two people’s heads
Capabilities
What Enterprise Legacy Migration covers
Each of these is staffed by people who have shipped it before. If a capability below is not relevant to your problem, we will take it out of the scope and the price.
Strangler fig execution
A routing seam in front of the legacy system, then extraction slice by slice with traffic flippable per route, per tenant, per percentage, without a deploy.
Data migration and dual-run
Change data capture, dual-write with hourly reconciliation, staged read-shift and explicit decommissioning of legacy columns so forgotten queries fail loudly rather than returning stale data.
Cloud replatforming
Landing zones, network and identity design, infrastructure as code, and a target architecture chosen for your operating model rather than for a reference diagram.
Knowledge recovery
Behaviour of undocumented systems reconstructed from code, logs and production traffic, then written down - often the first accurate documentation the system has ever had.
Delivery process
How the work runs, phase by phase
Dates, deliverables and exit criteria per phase. Nothing here is a placeholder. This is the plan we put in the statement of work.
- 01
Assessment
Four to six weeks. We read the code, trace the data, interview the people who know where the bodies are buried, and produce a sequenced plan with named risks and a cost range.
- 02
Build the seam
Routing layer in front of the legacy system carrying one hundred percent of production traffic to the unchanged monolith. Nothing else starts until this is boring.
- 03
First slice
A low-risk, high-signal capability extracted end to end, exercising auth, observability, deployment and rollback. It proves the pattern and calibrates the estimates for everything after it.
- 04
Extract and shift data
Slice by slice, with each owned table moving through dual-write, read-shift and legacy decommissioning. Traffic percentage on new services is published as the single programme metric.
- 05
Decommission
The legacy system is switched off deliberately, in stages, with the last dependencies tracked to zero. Decommissioning is scoped work with a date, not something that happens eventually.
Technology
The stack we bring to this work
Defaults, not dogma. If your organisation is standardised on something adjacent, we will work in it and tell you honestly where it will cost you.
- Java
- .NET
- Go
- TypeScript
- Kafka
- Debezium
- PostgreSQL
- Oracle
- Kubernetes
- Terraform
- AWS
- Azure
Questions
Enterprise Legacy Migration: the questions we get asked first
The answers we would give you on a call, written down. More at the full FAQ page.
For a substantial enterprise system, twelve to twenty-four months to the point where the legacy platform can be switched off. The first user-visible improvement lands in weeks, which is deliberate - a programme that shows nothing for a year does not survive its own budget review.
Yes, and you should. Feature freezes leak, and a frozen system drifts from the replacement being built against it. We sequence extraction so feature work happens in the new services wherever possible, which also pulls migration forward.
That is the normal case, not the exception. We reconstruct behaviour from source, database state, logs and mirrored production traffic, then verify the new implementation by comparing responses against the legacy system on live requests before any traffic shifts.
Occasionally. If the system is small enough that a rewrite is under four months for the team you actually have, the overhead of dual-running is not worth paying. We will say so, even though it is a smaller engagement for us.
Related services
What teams usually pair this with
Most engagements start in one service line and end up spanning two. Here is the rest of the catalogue.
Enterprise Legacy Migration
Ready to talk about enterprise legacy migration?
Tell us the system, the constraint and the deadline. You will get a written response from an architect within one business day, and an honest answer about whether we are the right firm for it.
Direct line:moeed@moreinns.com