Legacy Rebuild
Modernize the system that runs your business without a risky big-bang rewrite. Strangler-pattern migrations, parallel runs, safe data moves, and the test coverage that lets your team ship again.
Reply within 1 business day · US senior team · You own the code.
Sound Familiar?
What an aging system actually costs
Adding any feature takes a quarter
A request that should take a week takes three months. Every change ripples through code with no tests and no documentation. The team budgets for two days of work and eight days of fixing whatever else broke. Velocity has decayed to the point where the roadmap no longer matters — only the bug queue does.
The original developer is gone and nobody can read the code
The system was written by one person years ago. They left. What remains is unreadable to your current team — undocumented conventions, custom abstractions, a framework version nobody uses anymore. Onboarding any new engineer takes months because there’s nothing to onboard them onto.
Performance is so bad your team avoids the system
Pages take fifteen seconds to load. Reports time out. Searches return errors at scale. Your team has built workarounds — exporting data to Excel, keeping personal spreadsheets, calling each other instead of logging into the system. The software your business depends on has become the thing your business routes around.
Modernizing in-place is impossible because every change breaks something
You’ve tried to upgrade the framework, refactor the data layer, or rewrite the worst module. Every attempt surfaced more broken assumptions than it fixed. There’s no test suite to tell you what’s broken until a customer reports it. You’re stuck — too risky to change, too painful to keep.
What We Build
A modernization that doesn’t break the business
Strangler-pattern migration from your old stack to a modern one
We don’t do big-bang rewrites — they fail. We strangle the old system one route, one module, one workflow at a time. The legacy app keeps running until the new one is provably better at the slice we’re replacing.
Parallel-run rollouts so nothing breaks at cutover
New code runs alongside old code, in production, with both writing to the database and only one serving users. We watch them diverge, fix the new path, then flip traffic over feature-flag by feature-flag. Cutover stops being a single risky day.
Data migration with rollback paths
Every migration script has a documented rollback. Every batch is checkpointed. We migrate in slices small enough to verify, with the ability to revert any slice without taking the system down. No migration goes to production without a tested rollback already in place.
API layer that lets old and new coexist
We sit an API gateway in front of the legacy system so the new app can read and write the same data without forcing a flag day. Customers, integrations, and internal tools keep working against a stable contract while the implementation changes underneath.
Full test coverage so future changes are safe
Before we change behavior, we characterize the current behavior with tests. The test suite becomes the spec the legacy system never had. By the time the rebuild is done, you have CI that fails loudly on regressions — and your team can actually ship without fear.
A documented system at the end of it
Architecture diagrams, runbooks, deploy procedures, on-call playbooks, ADRs explaining the why behind the decisions. When we leave, your team or your next hire can read what you have, understand it, and keep building.
What’s included at the Atelier tier
Your fractional product team for the migration
Legacy rebuilds are the one category where we recommend Atelier from day one. The reasons are below — but the short version is: you need on-call coverage and architectural oversight while two systems run in parallel, and that’s exactly what Atelier is built for.
Recommended Tier
Most legacy-rebuild clients land on Atelier
A rebuild is always at least three concurrent tracks: the new app, the migration scaffolding, and the operational work to keep the old system stable while we’re replacing it. Atelier’s three-initiative cap and 24/7 on-call coverage are the floor for doing this safely.
Studio ($7,500/mo) can work for a narrow scope — say, rebuilding one module of a larger system that the rest of the business doesn’t touch. But for anything load- bearing, you want the fractional-CTO seat and the SRE coverage. The cost of getting modernization wrong is much higher than the $2,500/mo delta.
First deploy
Week 1
Atelier tier
$10,000/mo
60-day initial commit, then pause or cancel month-to-month.
Keep Exploring
Other ways we help operator-owners
Compare the tiers and what each includes on the pricing page, or see how hiring in-house compares to a retainer.
Let’s talk about your legacy system
Book a free 30-minute call. We’ll walk through the current stack, what you’ve already tried, and the shape a safe migration would take.
Reply within 1 business day · US senior team · You own the code.