What We Solve · Legacy Modernization

The system nobody
wants to touch.
Make it cheaper to run.

Every growing company eventually has one: a system that runs the business but that nobody dares to change. The original developers are gone, the documentation is stale, and every edit is a held breath. A full rewrite is too expensive and too risky. There's a third option — a senior engineer who learns the system from the inside, builds the context an AI can work from, and modernizes it in careful, tested steps. The business never stops running.

Start with a $5K system review See how we work →

This isn't theory

Eighteen years modernizing one system — without ever stopping it.

"Tim wasn't looking for a vendor to deliver a quick rewrite. He was looking for a partner — one who could understand the weight of his company's legacy and help carry it forward with care and precision." — Formpak · UK

Over eighteen years, the same core team modernized Formpak's entire platform while the business kept running every single day. Windows to Linux. Containerized with Docker. The database migrated from DB2 to MSSQL and PostgreSQL. Java upgraded from 1.5 through to 17, across many generations of the stack. AI-assisted development introduced to make the work faster and the system easier to maintain.

None of it happened as a single disruptive rewrite. Each evolution was phased, tested, and rolled out carefully — so the platform stayed continuous while it changed underneath. Formpak grew from a handful of clients to more than a hundred. The team didn't just maintain the software; they came to understand the business.

Happening right now

A ten-year-old product. A team that had said no to AI.

A SaaS company with a product nearly ten years old and a fifteen-person engineering team had, until recently, resisted AI entirely. They added a single Core70 engineer — not to rewrite anything, but to use AI to raise code quality and security on an established codebase. Within weeks, the team itself had started adopting AI in their own work.

This is what modernization usually looks like in practice: not a dramatic replacement, but one engineer showing a cautious team that the system can get safer and easier to work with — without putting the business at risk.

How it actually works

Knowledge first. Then code.

A legacy system is dangerous to change because the knowledge of how it works has leaked away. So that's where we start. A senior engineer learns your system from the inside and builds a structured knowledge base — the business rules, the dependencies, the reasons things are the way they are. With that context in place, AI becomes genuinely useful: it can help reason about impact, generate routine changes, and surface what a rewrite-from-scratch would have missed. The engineer stays focused where judgment matters — architecture, business logic, the decisions a model shouldn't make alone.

We're applying the same approach to our own twenty-year-old internal system right now — so we know exactly what we're asking you to take on.

This is part of how we build everything. See our full approach →

Start with a $5K system review.

You don't have to commit to a modernization program to find out whether this works. For $5,000, a senior engineer spends focused time inside your system — learning how it works, mapping the risks, and understanding what modernizing it would actually take. You get a written Modernization Roadmap — the system's real condition, the risks, and the path forward — not a sales pitch. If it makes sense to continue, the same engineer keeps going, billed by time, not locked into a fixed scope. Most of our long-term engagements started exactly this way.

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