Limewater Labs
Legacy modernization

Bring your critical system into the modern era — without disruption.

We build around the proven core, incrementally, persona by persona. The business keeps running the whole time, and each piece ships the moment it's done — no big-bang gamble, no cut-over weekend.

Where this usually starts

The system works. That's exactly what makes it hard to touch.

Our core system is decades old — and the people who built it are gone.

A rewrite means a cut-over weekend the business can't survive.

Nobody can tell us what the system actually does anymore.

The last modernization ran for years and shipped a coat of paint.

How we do it

Don't migrate the software. Modernize the business.

A migration that moves the same workflows to a newer stack is money spent for no new value. Every piece of work we take on has to answer one question first: what capability or revenue does this unlock?

Build around the core, not instead of it

A system with decades of domain knowledge and hundreds of live installations is a foundation, not a liability. Throwing it out discards the most expensive thing you own — thirty years of encoded know-how.

Old and new run side by side

The strangler fig: new add-ons take over one workflow at a time while the legacy system keeps serving the rest. The same function can live in both during the transition, so there is never a cut-over moment.

Add-ons shaped around one person's job

A phone for the warehouse person scanning barcodes, a tablet with big buttons for point of sale, a dense screen for finance — instead of one interface forced to serve everyone.

Specifications before code

With AI the code is the cheap part; deciding what to build is not. We reverse-engineer validated specifications out of the legacy source first — generate, review, regenerate — which is where AI actually pays off on a migration.

Keep your team's skills and your customers' configuration

We choose paths that reuse the code and skills you already have — for a .NET shop that usually means staying in C# with Blazor Hybrid and .NET MAUI. Backward compatibility is a hard constraint, not a nice-to-have.

Cloud as a premium option, not a mandate

Web and mobile do not require the cloud. Customers who want it pay for it, on-premise customers keep what they have — so modernization opens a revenue line instead of reading as a migration tax.

Under the hood: Strangler Fig · .NET MAUI + Blazor Hybrid · spec-first AI migration · Playwright AI + MCP on legacy desktop UI
What the first nine months look like

Value in months, not a multi-year death march.

  1. Week 1

    Design sprint

    Map the personas, brainstorm the add-ons that would serve them, prioritise, and validate with real customers — before anyone commits to build.

  2. ~1 month

    Clickable prototype

    The highest-value, highest-pain workflow, made real. Stakeholders are convinced by seeing it, not by a deck.

  3. 3–4 months

    A beta you can sell

    A minimum marketable product: demonstrable, billable, and in front of customers while the rest of the system carries on untouched.

  4. 9 months max

    In production

    Every add-on is time-boxed. We don't take on initiatives that disappear into development for two or three years before anyone sees value — those are the modernizations that fail.

Proof, not adjectives

We have done this on a live system.

Enterprise ERP modernization

A 30-year-old core system, modernized without downtime

Constraint
A ~30-year codebase across multiple legacy layers, a scattered database, and a hard deadline — with the business running on it every day.
Approach
Incremental, persona-based add-ons around the proven core. AI-assisted discovery to reverse-engineer specs from code no one fully remembered.
Result
A modernization that ships value in months, funds itself through new premium modules, and never forces a risky cut-over.

And before any of it was funded: in a day-and-a-half hackathon we rebuilt the core of a single screen whose logic was spread across three legacy layers, AI-assisted at every step. The point wasn't the screen — it was showing the client, in days, that the migration was real and achievable.

Client work is confidential; described here in general terms. See all three engagements — or the two people who would do the work.

Start a conversation

Tell us about the system that's keeping you up at night.

Start with a low-commitment modernization risk assessment: we look at what the system does, what it would take to modernize it incrementally, and give you a straight answer about what's worth doing.

Email us to get startedhello@limewaterlabs.com