A migration sequence
Which capability moves first, what it depends on, and what has to be true before the next slice starts. Ordered by risk retired per quarter, not by what is easiest.
Rescue and modernize
Modernize a systemthat is too important to switch off.
The systems most worth modernizing are the ones nobody is allowed to interrupt. Legacy Modernization moves capability off them in slices, against milestones, with the old system still running the business the whole way.
Every mark here links to the engagement it belongs to. See the work →
Legacy Modernization moves capability off a system that is slowing a business down, one measurable slice at a time, over two or more quarters, priced to the outcome after a free initial audit and billed against agreed milestones. There is no cutover weekend: the old system keeps running while capability is migrated behind stable boundaries. The engagement suits critical, often regulated systems that cannot pause and where delivery risk is compounding.
Choose thiswhen
- The system is critical and cannot pause
- Delivery risk and technical debt keep growing
- The estate is regulated or audit-sensitive
You get
A migration sequence and architecture boundaries, incremental cutover with no big bang, and data and audit continuity throughout.
Pricing
Priced Outcome
Billed against agreed milestones.
One agreed price for an agreed outcome, quoted after a free initial audit and approved before delivery begins.
What the estimate depends on- The scope of the outcome you want
- The stage the application is at
- The condition of the existing codebase
- The team the work requires
- How the system is used in production
- The operational complexity around it
Work out what it has to return first: the ROI calculator for operational work, how we measure for everything else.
Deliverables
What weactually deliver
Architecture boundaries
Seams placed so the old and new systems can run side by side, with traffic moved deliberately rather than all at once.
Incremental cutover
Each slice goes live on its own, behind its own switch, with its own way back. There is no weekend where everything changes.
Data and audit continuity
Records stay queryable and provable across the boundary for the whole migration, which is usually the constraint that decides the sequence.
Where it starts
The four places thisusually shows up
Operations
Work moves between people by hand, and every handoff can stall.
- The same record is typed into two systems
- A spreadsheet sits between two applications
- Volume grows, headcount is the only lever
Finance operations
Invoices and approvals depend on somebody remembering to check a folder.
- Month end is a week of copying
- Approvals live in an inbox rather than a system
- Nobody knows the cost per document
Customer support
The answers exist, in documents and past tickets, and finding them is the job.
- The same answer is rewritten daily
- Response time depends who picks it up
- The demo worked, production did not
Reporting and data
The number the business runs on is assembled by hand, twice, differently.
- A report is rebuilt weekly from exports
- Two dashboards disagree
- The data cannot be queried safely
Is this the right engagement for you?
Describe what is actually going wrong. We come back with the outcome, the engagement that fits and the price basis - after a free initial audit.
Recognise this?
Where a system too risky to changeusually shows up
Every change costs more than the last oneThe estimate for a small feature keeps growing, and nobody can point at the line where it started.01
One person understands itThe system is documented by a single long-tenured engineer, and the business quietly plans around their holidays.02
The platform is out of supportA runtime, database or framework is past end of life, so a security patch is now a migration project.03
A big-bang replacement was triedIt ran long, the business kept moving, and the replacement was obsolete before it was finished.04
Audit is the blockerThe system holds records somebody regulated will ask about, so any change has to prove data and audit continuity before it is allowed.05
How we decide
The migration is judged on risk retired, not on code moved.
A modernization that ports half the system and retires none of the risk has spent two quarters buying nothing. The sequence is chosen by what stops being dangerous, and the milestones bill against exactly that.
- Every slice retires a named risk, agreed in writing before it starts.
- The old system keeps running until the new one has carried real traffic.
- Each cutover has a rollback that has actually been exercised.
- If a slice turns out not to be worth migrating, it is left alone and the money goes to the next one.
In practice
What fixing a system too risky to changelooks like
Boundary → proxy → new service → traffic shift → retire
Strangling a monolith
Requests are routed at a seam, the new implementation takes a fraction of them, and the old path is removed only once the new one has proven itself in production.
Inventory → compatibility → staged upgrade → verification
The end-of-life runtime
An unsupported platform is upgraded in stages against a test suite built for the purpose, rather than in one jump nobody can review.
Dual write → reconcile → read switch → single source
Data on both sides
Writes go to both systems while they are reconciled, so the read switch is a decision rather than a leap.
Historic records → mapped schema → parallel reports → sign-off
Reporting that must not break
The reports an auditor asks for are produced from both systems and compared before anything is retired.
Questions
About a system too risky to change
Priced Outcome, like the other five, and then billed against milestones. The free initial audit comes first and the scope and cost are approved before delivery begins; each milestone after that is a slice of capability with a named risk it retires, so payment tracks progress that can be pointed at rather than time elapsed.
Yes, and that is the point of working in slices. The old system keeps taking changes while capability moves behind stable boundaries. A modernization that requires the business to stop is a rewrite wearing a different name.
The first milestone lands inside the first quarter and retires a real risk. If the sequence is right you get value from slice one, and if it is wrong you find out early enough to change it cheaply.
Data and audit continuity is treated as a constraint on the sequence rather than as a task at the end. In practice it usually decides which slice can move first.
Not this one?
The otherengagements
Our roadmap needs a senior team behind it.AI-Native Engineering Pod3 months minimumPriced OutcomeThe AI demo has to work in production.AI Integration Sprint4-8 weeksPriced OutcomeManual work is eating our capacity.Agentic Workflow Automation8-12 weeksPriced OutcomeThe prototype cannot survive real users.Vibe Code Rescue Sprint4-6 weeksPriced OutcomeNobody owns the product after launch.Product CareOngoingPriced Outcome
Before you commit
What you wouldbe signing up for
One bounded outcome
A named result, a fixed window and a scope agreed in writing before delivery starts.
- Commitment
- 4 to 12 weeks
- Price basis
- Priced Outcome
- The problem has an edge you can describe
- You want the cost known first
- Someone inside owns the result
A team against a roadmap
Senior capacity inside your codebase, moving a roadmap week after week.
- Commitment
- 3 months minimum
- Price basis
- Priced Outcome
- The work is continuous, not bounded
- Recruiting would cost a quarter
- You want the same people throughout
Ownership after launch
Monitoring, patching, upgrades and a named engineer for live software.
- Commitment
- Ongoing, cancellable
- Price basis
- Priced Outcome
- It is live and business-critical
- Nobody owns it out of hours
- The risk needs an owner
One agreed price for an agreed outcome, quoted after a free initial audit and approved before delivery begins.
Named quotes go here as clients approve them. See what the engagements produced →
Next step
Have a system everyone agrees should be replaced and nobody dares to touch?
Tell us what it does and what would happen if it stopped. We will come back with the first slice worth moving and the risk that moving it retires.