Accelerated UI Modernization: Turning Video Records into Production-Ready React

The average enterprise rewrite fails long before the first line of new code is even committed. It fails during "archaeology"—the months-spent-in-meetings phase where developers try to decipher 15-year-old COBOL-backed UI logic with zero documentation. With a global technical debt mountain reaching $3.6 trillion, the "Big Bang" rewrite is no longer a viable business strategy; it is a fiduciary risk.

TL;DR: Accelerated UI modernization leverages visual reverse engineering to transform video recordings of legacy workflows into documented, production-ready React components, reducing migration timelines from years to weeks.

The Archaeology Trap: Why 70% of Modernization Projects Fail#

Most legacy systems are black boxes. According to industry data, 67% of legacy systems lack any form of up-to-date documentation. When a CTO mandates a "modernization," the engineering team typically defaults to manual reverse engineering. This process—interviewing users, digging through undocumented SQL stored procedures, and trying to replicate UI states—takes an average of 40 hours per screen.

In a typical enterprise application with 200+ screens, you are looking at 8,000 man-hours just for discovery. This is why the average enterprise rewrite timeline stretches to 18–24 months, and why 70% of these projects either fail or significantly exceed their budgets.

The Cost of Manual Modernization#

⚠️ Warning: Attempting a "Big Bang" rewrite without a documented source of truth for your business logic is the primary cause of budget overruns in Financial Services and Healthcare migrations.

Accelerated UI Modernization: The Visual Approach#

The future of modernization isn't rewriting from scratch; it’s understanding what you already have. Replay introduces a paradigm shift: Visual Reverse Engineering. Instead of reading dead code, we record live user workflows. By capturing the DOM transitions, state changes, and network calls in real-time, Replay generates a technical blueprint of the legacy system.

From Video to React: The Technical Pipeline#

When you record a legacy workflow—whether it's an old Java Applet, a Silverlight tool, or a legacy JSP site—Replay’s AI Automation Suite analyzes the execution trace. It doesn't just "take a screenshot"; it identifies patterns, component boundaries, and data dependencies.

Step 1: Workflow Recording

The process begins by recording a standard business process (e.g., "Onboarding a new insurance claimant"). Replay captures the "Flows"—the architectural map of how a user moves through the system.

Step 2: Component Extraction

Replay's "Blueprints" engine identifies repeated UI patterns. If a specific data table appears across ten screens, Replay recognizes it as a single candidate for your new Design System (Library).

Step 3: Code Generation

The system outputs clean, modular React components. Unlike "low-code" tools that spit out unreadable spaghetti, Replay generates TypeScript code that follows modern best practices: functional components, hooks for state management, and clear prop definitions.

typescript
// Example: React component generated via Replay Visual Extraction
// Source: Legacy Claims Management Portal (v4.2)

import React, { useState, useEffect } from 'react';
import { Button, TextField, DataGrid } from '@your-org/design-system';
import { fetchClaimDetails, updateClaimStatus } from '../api/claims-proxy';

interface ClaimProps {
  claimId: string;
  onSuccess: () => void;
}

/**
 * @generated Generated by Replay AI Automation Suite
 * @description Preserves legacy validation logic from 'claims_validator_v2.js'
 */
export const LegacyClaimForm: React.FC<ClaimProps> = ({ claimId, onSuccess }) => {
  const [data, setData] = useState<any>(null);
  const [loading, setLoading] = useState(true);

  useEffect(() => {
    async function load() {
      const result = await fetchClaimDetails(claimId);
      setData(result);
      setLoading(false);
    }
    load();
  }, [claimId]);

  const handleApprove = async () => {
    // Business logic extracted from legacy 'btnApprove_OnClick'
    if (data?.status === 'PENDING' && data?.totalAmount < 5000) {
      await updateClaimStatus(claimId, 'APPROVED');
      onSuccess();
    }
  };

  if (loading) return <p>Loading legacy state...</p>;

  return (
    <div className="p-6 bg-white rounded-lg shadow">
      <h2 className="text-xl font-bold mb-4">Claim: {data?.referenceNumber}</h2>
      <TextField label="Adjuster Notes" value={data?.notes} multiline />
      <div className="mt-4 flex gap-2">
        <Button variant="primary" onClick={handleApprove}>
          Approve Claim
        </Button>
      </div>
    </div>
  );
};

💡 Pro Tip: Use Replay’s "Blueprints" to identify "Ghost Logic"—features that exist in the code but are never touched by users during recordings. This allows you to aggressively prune technical debt during the migration.

Bridging the Documentation Gap#

The most significant risk in modernization is losing the "Why" behind the "How." Legacy systems are often the only repository of complex business rules—tax calculations, regulatory compliance checks, or manufacturing tolerances.

Replay solves this by generating API Contracts and E2E Tests directly from the recorded sessions.

1. •API Contracts: Replay monitors the network tab during recording, mapping every request/response to the legacy backend. It generates Swagger/OpenAPI specs that serve as the bridge for your new frontend.
2. •E2E Tests: The recording is converted into Playwright or Cypress scripts. This ensures that your new React UI behaves exactly like the legacy system, providing 1:1 functional parity.
3. •Technical Debt Audit: Replay flags redundant components and inconsistent UI patterns, allowing you to consolidate 50 different "Submit" buttons into a single, governed component in your Replay Library.

💰 ROI Insight: Companies using Replay see an average of 70% time savings. For a mid-sized migration, this translates to saving approximately $450,000 in engineering salaries and overhead.

Implementation Roadmap: The 4-Week Modernization#

Modernizing a core module (e.g., a Financial Ledger or Patient Records portal) follows a streamlined path with Replay.

Step 1: Assessment & Recording#

Subject Matter Experts (SMEs) record their daily workflows using Replay. There is no need for source code access at this stage. Replay builds the "Flows"—a visual map of the application architecture.

Step 2: Extraction & Blueprinting#

The Replay engine parses the recordings. It identifies the "Atomic" elements (inputs, buttons) and "Molecular" elements (forms, tables). These are exported to the Replay Library, forming the foundation of your new Design System.

Step 3: Logic Mapping & Testing#

Replay generates the API proxy layer and the testing suite. Developers review the generated React components, ensuring that state transitions match the legacy behavior.

Step 4: Deployment#

The new React components are deployed, often using a "Strangler Fig" pattern where the new UI sits on top of the legacy backend, gradually replacing old screens without a single day of downtime.

📝 Note: Replay is built for regulated environments. Whether you are in Government, Telecom, or Insurance, Replay offers On-Premise deployment and is SOC2 and HIPAA-ready to ensure your sensitive workflow data never leaves your perimeter.

From Black Box to Documented Codebase#

The goal of Accelerated UI Modernization is not just to "look newer." It is to move from a state of high-risk dependency on "tribal knowledge" to a state of engineering excellence.

When you use video as the source of truth, you eliminate the ambiguity of manual requirements gathering. You aren't asking a developer to "guess" what a button does; you are showing the machine what it does, and letting the machine write the boilerplate.

• •Financial Services: Rapidly move from mainframe-backed green screens to modern React dashboards while preserving complex interest calculation logic.
• •Healthcare: Transition legacy EHR systems to mobile-responsive interfaces without risking patient data integrity.
• •Manufacturing: Modernize shop-floor inventory systems that were built for Windows XP, bringing them into the web era in weeks.

Frequently Asked Questions#

How long does legacy extraction take?#

While a manual rewrite takes 40+ hours per screen, Replay reduces this to approximately 4 hours. A standard module of 20 screens can be fully documented and extracted into React components in about two weeks.

What about business logic preservation?#

Replay captures the actual execution of business logic. By generating E2E tests based on real user interactions, we ensure the new system produces the same outputs as the legacy system. If the legacy system has a specific "quirk" in how it handles data validation, Replay flags that logic for inclusion in the modern component.

Does Replay require access to my legacy source code?#

No. Replay performs "Visual Reverse Engineering." It analyzes the rendered output and the data layer (DOM and Network). This makes it ideal for modernizing third-party legacy tools or systems where the original source code has been lost or is too brittle to touch.

Is the generated code maintainable?#

Yes. Unlike "no-code" platforms, Replay generates standard TypeScript/React code. It uses your existing Design System (or helps you build one in the Replay Library) and follows clean architecture principles. Your team owns the code; there is no vendor lock-in.

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