Modernization without the rewrite.
Legacy codebases re-platformed incrementally — strangler-fig migration, parallel running, no feature freeze. We've done enough of these to know which patterns work and which produce the second failed rewrite in a row.
The problem we solve
Most legacy modernization is announced as a rewrite, runs for two years, ships nothing usable, and ends with the original system still in production. We don't do rewrites. We strangle the legacy system service by service, with parallel running, behind feature flags, while you keep shipping product. The legacy code retires when the new code has earned the traffic — not when the project plan says it should.
What we do
- 01Strangler-fig migration patterns at code, service and data level
- 02Anti-corruption layers between legacy and modern systems
- 03Database modernization with dual-write and back-fill strategies
- 04API translation between legacy and modern contracts
- 05Feature-flagged incremental cutover
- 06Parallel running with consistency comparison
- 07Test coverage retroactively built around legacy behaviour
- 08Documentation of legacy behaviour — frequently the first time it's written down
- 09Honest assessment of what can be modernized vs what should be retired
What you receive
- Phased migration plan with risk and rollback at each step
- Modernized system running in parallel until confidence is built
- Documented legacy behaviour your team can defend
- Retirement plan for the legacy system
Patterns we use
Ideal for
- → Companies with 5+ year-old codebases slowing every change
- → Teams whose previous rewrite attempt failed
- → Engineering leaders inheriting legacy systems they can't risk replacing
- → Companies under acquisition pressure to modernize
How an engagement runs
- 01
Map the legacy
Document what's actually in there — behaviour, integrations, hidden contracts. Often the first time it's written down.
- 02
Plan strangulation
Which slices migrate first, in what order, with what fallback. Written plan signed by leadership.
- 03
Migrate in slices
Service by service, behind feature flags, with parallel running until confidence is built.
- 04
Retire
Legacy code retired only after the new code has earned the traffic.
How to engage
Modernization Strategy
Written assessment, target architecture and phased plan.
Modernization Programme
Phased execution alongside your team, with quarterly milestones.
Surgical Modernization
One specific subsystem extracted and modernized.
Frequently asked.
01Will you recommend a rewrite?
Almost never. Rewrites fail at high rates and almost always cost more than incremental migration. We'll tell you when a rewrite is genuinely the cheaper path — but it's rare.
02Can we keep shipping product during this?
Yes — that's the entire point of strangler-fig. We never need a feature freeze.
Have a problem worth solving well?
Tell us the outcome you want. We'll tell you what it takes — honestly, within a week, in writing.
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