WinForms to React: The Essential Guide to Modernizing Pharma Lab Information Systems (LIMS)

70% of legacy modernization projects fail or exceed their timelines, and in the pharmaceutical industry, a failed migration isn't just a budget overrun—it’s a regulatory catastrophe. For Lab Information Systems (LIMS) built on the aging .NET WinForms framework, the technical debt has become a literal barrier to scientific innovation.

The $3.6 trillion global technical debt is nowhere more visible than in the pharmaceutical lab. Scientists are tethered to desktop workstations running WinForms applications designed in the mid-2000s, unable to access critical sample data from mobile devices or integrate with modern cloud-based analytics. The mandate is clear: you must move from WinForms to React, but the traditional "rip and replace" strategy is a suicide mission.

TL;DR: Modernizing Pharma LIMS from WinForms to React no longer requires a 24-month "Big Bang" rewrite; by using visual reverse engineering with Replay, teams can extract business logic and UI patterns directly from user workflows, reducing migration time by 70%.

The WinForms to React Transition: Why Now?#

WinForms was the gold standard for high-throughput data entry in the early 2000s. It handled complex grids and hardware integrations with ease. However, as Pharma 4.0 takes hold, the limitations of desktop-bound LIMS are glaring:

1. •Zero Mobility: Scientists cannot update sample status at the bench or in the cold room.
2. •Integration Silos: Modern lab equipment speaks JSON and REST; WinForms lives in a world of SOAP and direct SQL connections.
3. •The Talent Gap: Finding engineers who want to maintain C# 2.0 code is becoming impossible.
4. •Documentation Archaeology: 67% of these legacy systems lack any meaningful documentation. The original architects have retired, leaving behind a "black box" that runs the entire lab.

The move from WinForms to React is the essential guide to unlocking this data. But the path is fraught with risk. An 18-month average enterprise rewrite timeline is too slow for a fast-moving clinical trial.

The "Black Box" Problem in Pharma LIMS#

In a regulated Pharma environment, you cannot afford to guess what a button does. A WinForms "Submit" button in a LIMS might trigger a chain of events: updating a SQL table, triggering an audit trail entry, sending an alert to a Quality Assurance (QA) queue, and interfacing with a thermal cycler.

When you begin modernizing these systems, you realize the code is often "spaghetti" where business logic is tightly coupled with the UI layer (the

and files).

⚠️ Warning: Attempting to manually document these workflows by reading legacy C# code is what we call "Software Archaeology." It is slow, prone to human error, and usually misses the edge cases that users have developed over a decade of use.

This is where Replay changes the math. Instead of reading code, Replay records the real user workflow. It watches the data move, the state change, and the UI react. It turns the "black box" into a documented React codebase.

Step-by-Step: Modernizing WinForms to React#

Step 1: Workflow Capture and Recording#

Instead of gathering requirements in a conference room, we record the scientists performing their actual tasks. In a LIMS environment, this might be "Accessioning a New Sample" or "Approving a Batch." Replay captures the DOM-like equivalent of the WinForms structure and the underlying data calls.

Step 2: Extracting the Design System#

WinForms applications are notorious for inconsistent UI. However, they usually follow a pattern. Replay’s Library feature identifies recurring UI patterns (grids, date pickers, sample status badges) and generates standardized React components.

Step 3: Mapping the Logic (The API Contract)#

WinForms often communicates directly with the database. For a modern React frontend, we need a clean API layer. Replay automatically generates API contracts based on the data observed during the recording phase.

typescript
// Example: Generated API Contract from a WinForms 'Sample Entry' workflow
// Extracted via Replay AI Automation Suite

export interface ILimsSample {
  sampleId: string;
  batchId: string;
  timestamp: string;
  scientistId: string;
  status: 'Pending' | 'In-Progress' | 'Completed' | 'Flagged';
  metadata: {
    temperature: number;
    reagentLot: string;
  };
}

export interface ISampleUpdateResponse {
  success: boolean;
  auditLogId: string;
  nextStep: string;
}

Step 4: Component Generation#

Once the data structures are defined, we move to the UI. Manual conversion of a complex WinForms screen to React takes an average of 40 hours. With Replay, this is reduced to 4 hours.

tsx
// Example: Generated React component for a LIMS Sample Dashboard
// This preserves the business logic captured from the legacy WinForms event handlers

import React, { useState, useEffect } from 'react';
import { Table, Badge, Button } from '@/components/ui'; // From Replay Library
import { ILimsSample } from '@/types/lims';

export const SampleManagementDashboard: React.FC = () => {
  const [samples, setSamples] = useState<ILimsSample[]>([]);

  // Logic extracted from WinForms 'OnLoad' and 'Refresh' events
  const loadSamples = async () => {
    const data = await fetch('/api/v1/samples/active');
    const json = await data.json();
    setSamples(json);
  };

  return (
    <div className="p-6">
      <h1 className="text-2xl font-bold">Lab Sample Queue</h1>
      <Table data={samples}>
        <Table.Column header="ID" accessor="sampleId" />
        <Table.Column 
          header="Status" 
          render={(row) => (
            <Badge variant={row.status === 'Flagged' ? 'destructive' : 'default'}>
              {row.status}
            </Badge>
          )} 
        />
        <Table.Column 
          header="Actions" 
          render={(row) => (
            <Button onClick={() => handleAudit(row.sampleId)}>View Audit Trail</Button>
          )} 
        />
      </Table>
    </div>
  );
};

Bridging the Documentation Gap#

In the pharmaceutical industry, documentation is the product. If it isn't documented, it didn't happen. Legacy WinForms systems often suffer from a "documentation gap" where 67% of the system's logic exists only in the minds of the users or in unreadable source code.

Replay bridges this gap by providing Visual Reverse Engineering. It generates:

• •E2E Tests: Automatically creates Playwright or Cypress tests based on the recorded WinForms workflows.
• •Technical Debt Audit: Identifies which parts of the legacy system are actually used and which can be retired.
• •Architecture Flows: Visualizes how data moves through the system, essential for SOC2 and HIPAA compliance.

💰 ROI Insight: By automating the documentation and extraction phase, enterprise teams save an average of 70% in time. What used to be a 2-year roadmap is compressed into a single quarter.

Handling Regulated Environments (GXP/HIPAA)#

Pharma LIMS modernization requires more than just pretty buttons. You need a platform built for regulated environments. Replay is SOC2 compliant and HIPAA-ready, offering On-Premise deployment for companies that cannot have their source code or data leaving their firewall.

When moving from WinForms to React, the biggest risk is losing the "Audit Trail" logic. In WinForms, this was often handled via database triggers or tightly coupled C# logic. Replay’s Blueprint editor allows architects to verify that every critical data mutation in the new React app triggers the same audit events as the legacy system.

The Future Isn't Rewriting—It's Understanding#

The old way of modernizing involved a room full of consultants trying to guess what the software does. The new way is understanding what you already have through video as the source of truth.

By recording the "Video as source of truth," Replay allows you to see exactly how a scientist interacts with a complex WinForms grid, how they handle validation errors, and what hidden workflows they’ve created to get their jobs done. You aren't just moving code; you are preserving institutional knowledge.

💡 Pro Tip: Don't try to modernize the whole LIMS at once. Use Replay to extract the most high-value workflows first (e.g., Sample Results Entry) and deploy them as a React micro-frontend alongside your legacy WinForms app.

Frequently Asked Questions#

How long does the WinForms to React extraction take?#

While a manual rewrite of a complex LIMS screen can take 40+ hours, Replay reduces this to approximately 4 hours per screen. Most enterprise pilots see a fully documented and extracted core workflow in under two weeks.

Can Replay handle complex WinForms controls like DataGridView?#

Yes. Replay’s visual reverse engineering identifies the data patterns within complex controls like grids and tree views, mapping them to modern, accessible React equivalents (like TanStack Table) while preserving the original data binding logic.

How does this affect 21 CFR Part 11 compliance?#

By generating automated E2E tests and clear API contracts from the original workflows, Replay provides a "paper trail" of the migration. This makes the validation (IQ/OQ/PQ) process significantly faster and more accurate than manual documentation.

Do we need the original source code?#

While having the source code is helpful, Replay’s primary strength is its ability to reverse engineer from the running application. This is critical for legacy systems where the source code might be lost, or the build environment no longer exists.

What about business logic preservation?#

Replay captures the inputs and outputs of every user action. By analyzing the data traffic and state changes during a recording, the AI Automation Suite can reconstruct the business logic that governed the WinForms application, ensuring no "hidden" rules are lost in the move to React.

---

Ready to modernize without rewriting? Book a pilot with Replay - see your legacy screen extracted live during the call.