Systems that cannot go down, replaced while they run.

11 of 12 listed with consent to link

1. 01

   Discovery

   Four to six weeks with your engineers, your operators and your auditors, mapping the system as it actually behaves rather than as the documentation claims. We trace the real data flows, price the cost of doing nothing, and name the three failure modes most likely to hurt you first. You keep the survey — a written system map, a risk register and a costed set of options — whether or not you hire us for anything after it.

2. 02

   Architecture

   We design the target state and, more importantly, the sequence that gets you there while the current platform stays up. Migration order, dual-run boundaries, rollback points, and where the regulatory controls attach. You keep the architecture, the sequenced plan and the estimates behind it: enough to build it with your own team, put it out to tender, or hand it to another firm entirely.

3. 03

   Delivery

   Increments that reach production, typically every two weeks, each one reversible and each one running alongside the system it replaces until the numbers agree. Your engineers work in the same repository as ours from day one. You keep working software from week six rather than a demonstration at the end, and a shared codebase that is never ours to withhold.

4. 04

   Handover

   We rehearse the handover before we mean it: your team takes the pager while we are still on the call, then takes it for real. Runbooks tested by someone who has never seen the system, an alerting set that has been pruned rather than accumulated, and the test estate that makes the next change safe. You keep a platform your own people can run — our last invoice should be the last one you need to pay us.

You keep — survey · architecture · working software · a platform your own team runs

• 2026-05-19Engineering

  Reading a COBOL codebase you did not write

  The programs are the last thing to read. Start with the job control and the copybooks, because that is where forty years of business rules were actually written down.

  By Halvard Bruun

  5 min read→
• 2026-02-10Reliability

  Cutover rehearsals, and why we do six

  A 412-step runbook took 19 hours on its first rehearsal against a 9-hour window. By the sixth it took 6 hours 40. The rehearsals were not practice — each one was designed to fail differently.

  By Priya Raghunathan

  5 min read→
• 2025-11-18Engineering

  The integration nobody documented

  Every legacy platform has interfaces that appear in no diagram and no register. Here is how we find them before cutover finds them for us — and why the interface diagram is the last place to look.

  By Halvard Bruun

  4 min read→