Verified migration

Legacy application modernization

The system works, and that is exactly the trap. It cannot hire, it cannot scale, it will not pass its next security review, and every year it keeps running makes the migration more expensive.

What we do

Modernization as a sequence of provable steps rather than a big-bang rewrite: strangler patterns that retire the old system a seam at a time, data migrations rehearsed until they are boring, and behaviour verification so the new system demonstrably does what the old one did. Our verification tooling exists because "the tests pass" is not the same as "nothing changed".

Strangler or rewrite: how we decide

The default is incremental, because a running business cannot stop for a rewrite and a rewrite’s risk arrives all at once at the worst moment, cutover. We map the system’s seams, put a routing layer in front, and move capability across one seam at a time, with the old system as the safety net until each piece earns retirement.

A full rewrite is right when the platform itself is terminal: an unsupported runtime, a dead vendor, a security posture that cannot be patched. When we recommend one, it comes with the reasons in writing and a bridge plan for the years the two systems coexist.

Verified migration, our actual differentiator

AI can now translate a COBOL codebase to Java in days. It cannot prove it did not break anything, and neither can a green test suite that only covers what someone thought to test. We built the verification layer for exactly this gap: parallel runs against production traffic, systematic output diffing, and behavioural comparison at the seams, so cutover happens when the evidence says the systems agree, not when the calendar says time is up. The tooling is public because a claim like this should be checkable.

What migration looks like from your side

Reads move first because they are reversible. Writes follow with fallback paths held open. Data migrates in rehearsed, resumable steps with reconciliation reports after each. Business operations continue throughout, and the moments of genuine risk are scheduled, announced and reversible. We aim for boring, because a migration that makes headlines inside your company has already failed.

Questions we hear before engagements

How long does modernization take?

Seams start moving within the first quarter. Whole-system timelines depend on how much behaviour has to be preserved, and the assessment phase prices that honestly before you commit to the whole journey.

Will there be downtime?

Cutover moments are scheduled and short; the strangler approach exists so that the business never runs without a working system.

Can we fund it incrementally?

Yes, and you should. Each retired seam is a delivered unit of value, which means the program can pause at any seam without stranding the investment.

Our system runs on COBOL, PowerBuilder or a dead vendor’s product. Is that a problem?

It is the usual case. The method does not care about the source technology; it cares about observable behaviour, which every running system has.

Related capability

If your system has to be right, let’s talk.

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