012–3 weeks
Audit
We read the code, map the data and integrations, interview the people who use it, and rank what must survive.
Legacy Modernization
A modern system in production, migrated from one that is failing, with no downtime for users and nobody left guessing how it works, over five to twelve months.
The buyer question this answers: Our old system is dying. Can you fix it without downtime?
Who this is for
- A system that runs the business and that nobody left understands.
- Software on a platform, framework, or vendor that is reaching end of life.
- A product that cannot add features because every change breaks something.
Phase by phase
Reference timings for a typical engagement. The written scope gives you the dates for yours.
- 022 weeks
Target architecture and plan
The new architecture, the migration strategy, and the order in which pieces move.
- 0312–24 weeks
Strangler build
New components replace old ones behind the same interfaces, one at a time, with both running side by side.
- 043–4 weeks
Data migration
Data is cleaned, migrated, and reconciled, with rehearsals until the numbers match.
- 051–2 weeks
Cut-over
The last traffic moves, the old system goes read-only, then off, with a rollback ready.
- 064 weeks
Stabilise and hand over
Monitoring, fixes, documentation, and your team taking the controls.
The stack for this workflow
- Python or Node.js
- PostgreSQL
- Kafka for staged data flows
- Docker
- Terraform
- GitHub Actions
- Grafana
- Sentry
- Contract tests against the old system
What could go wrong
Every build has risks. These are the ones we plan for on this kind of project, and what we do about each.
Undocumented behaviour the business depends on is lost.
How we handle itThe audit interviews the people who use the system, contract tests capture current behaviour, and old and new run side by side so differences show up before cut-over.
Data does not reconcile.
How we handle itMigration is rehearsed repeatedly and signed off on a reconciliation report before the real one.
The project becomes a rewrite that never ships.
How we handle itThe strangler approach puts replaced pieces into production as they are ready, so value arrives monthly, not at the end.
Cost model: Dedicated team
Legacy systems reveal surprises. A dedicated team with a staged plan absorbs them without re-quoting, and you see progress in production every month.
No prices on this page. The scope phase ends with a written quote for your project.
From the blog
- What we check before taking over someone else's codebaseThe audit we run in the first week on an inherited codebase: the eight questions we answer, in order, and what each one tells you about the months ahead.
- How to hand over a codebase so a team can run itOwnership is a clause; handover is the work that makes it real. The checklist we run at the end of every engagement so your team can run the system without us.
Questions we get asked
Rewrite or refactor?
Usually neither in full. The strangler approach replaces pieces behind stable interfaces, keeping what works and retiring what does not. The audit says which pieces.
Can we keep running during the migration?
Yes. That is the point of running old and new side by side. Downtime is designed out rather than scheduled.
What if nobody understands the old system?
That is common and it is why the audit exists. Code reading, data analysis, and interviews rebuild the understanding before anything is changed.
How long before we see anything?
The first replaced component is usually in production within the first two months of the build phase.
Tell us what you are building.
We reply within one business day with how we would build it, what it would cost, and which engagement model fits.
- 01Tell us what you are building
A short form or an email. No deck required, and "not sure yet" is a fine answer.
- 02A call with an engineer
Within one business day. Technical questions get technical answers, from the person who would build it.
- 03A written scope and quote
Fixed price where the scope is defined. The document is yours whether or not you go ahead.