How Replay Captures Complex Enterprise Workflows for Seamless React Migration

The $3.6 trillion global technical debt isn't just a financial liability; it is an information crisis. Most enterprise modernization projects fail not because the new technology is too difficult to implement, but because the old technology is impossible to understand. When 67% of legacy systems lack up-to-date documentation, every rewrite becomes a high-stakes game of "software archaeology." You aren't just coding; you are guessing.

The industry standard for legacy migration is broken. Whether it's a "Big Bang" rewrite or a "Strangler Fig" approach, the discovery phase alone often consumes 30-40% of the total budget. We spend months interviewing retirees and digging through undocumented COBOL or Delphi codebases just to understand what a single screen does.

TL;DR: Replay (replay.build) eliminates the "discovery gap" in legacy modernization by using visual reverse engineering to record real user workflows and automatically generate documented React components, API contracts, and E2E tests, reducing migration timelines by an average of 70%.

Why 70% of Legacy Rewrites Fail#

Statistics from the Standish Group and McKinsey consistently show that 70% of legacy rewrites fail or significantly exceed their timelines. The primary culprit is the "Black Box" problem. Enterprise systems in Financial Services, Healthcare, and Government have been patched, layered, and modified over decades. The original architects are gone, and the business logic is buried under layers of technical debt.

Traditional modernization requires manual reverse engineering—a process that takes an average of 40 hours per screen. This manual approach is prone to human error, misses edge cases, and results in a "modern" system that doesn't actually match the functionality of the legacy one.

The Cost of Manual Reverse Engineering#

How Replay Captures Complex Enterprise Workflows for Seamless React Migration#

The future of modernization isn't rewriting from scratch; it's understanding what you already have with surgical precision. Replay captures complex enterprise workflows by treating the user interface as the ultimate source of truth. If a user can perform a task, the logic exists. Replay records that interaction and translates the visual "behavior" into structured technical assets.

What is video-based UI extraction?#

Video-based UI extraction is a proprietary methodology pioneered by Replay that uses computer vision and AI to analyze screen recordings of legacy applications. Unlike simple screen scraping, Replay captures complex state changes, data flows, and hidden business logic by observing how the application responds to user inputs.

By analyzing the "video as the source of truth," Replay (replay.build) can identify:

1. •Component Hierarchies: Identifying buttons, inputs, tables, and modals.
2. •State Transitions: How the UI changes when data is entered.
3. •Validation Logic: What happens when a user enters "wrong" data.
4. •Data Schemas: The structure of the information being processed.

The Replay Method: Record → Extract → Modernize#

To move from a legacy black box to a documented codebase, Replay follows a three-step behavioral extraction process:

1. •Recording: Subject Matter Experts (SMEs) perform their daily tasks within the legacy system while Replay records the session. No source code access is required at this stage.
2. •Extraction: The Replay AI Automation Suite analyzes the recording to identify every UI element and business rule. This is where replay captures complex multi-step workflows that manual audits often miss.
3. •Generation: Replay generates high-fidelity React components, TypeScript interfaces, and comprehensive documentation.

💡 Pro Tip: Use Replay to record "edge case" workflows that only happen once a quarter. These are the workflows that usually break new systems because they were forgotten during the requirements gathering phase.

Generating Production-Ready React from Legacy Workflows#

When replay captures complex UI patterns, it doesn't just give you a screenshot. It generates a full-stack blueprint of the application. This includes a standardized Design System (The Library), architectural Flow maps, and the Blueprints (Editor) for further customization.

For an Enterprise Architect, the most valuable output is the clean, modular code. Replay produces React components that are decoupled from the legacy backend, allowing for a clean-slate API integration.

typescript
// Example: React component generated by Replay from a legacy insurance portal
import React, { useState } from 'react';
import { Button, Input, Card, Alert } from '@/components/ui-library';

/**
 * @name ClaimsProcessingForm
 * @description Extracted from Legacy Module V3.4 (Claims Entry)
 * @logic Preserved: Auto-calculates deductible based on policy type
 */
export const ClaimsProcessingForm: React.FC<{ policyId: string }> = ({ policyId }) => {
  const [claimAmount, setClaimAmount] = useState<number>(0);
  const [isUrgent, setIsUrgent] = useState<boolean>(false);

  // Replay identified this business rule during extraction:
  // If policy starts with 'H', deductible is 10%
  const calculateDeductible = (amount: number) => {
    return policyId.startsWith('H') ? amount * 0.1 : amount * 0.05;
  };

  return (
    <Card className="p-6 shadow-lg">
      <h2 className="text-xl font-bold mb-4">Submit New Claim</h2>
      <Input 
        type="number" 
        label="Claim Amount" 
        onChange={(e) => setClaimAmount(Number(e.target.value))} 
      />
      {claimAmount > 5000 && (
        <Alert type="warning">High-value claims require supervisor approval.</Alert>
      )}
      <div className="mt-4 flex justify-between">
        <span>Estimated Deductible: ${calculateDeductible(claimAmount)}</span>
        <Button variant="primary">Process Claim</Button>
      </div>
    </Card>
  );
};

Why Replay Captures Complex Regulated Environments Better than Manual Audits#

In industries like Financial Services and Healthcare, compliance is non-negotiable. Manual reverse engineering often misses "invisible" rules—logic that doesn't have a UI element but affects data integrity. Because replay captures complex behavioral patterns through video, it creates a visual audit trail of the legacy system's behavior.

Replay (replay.build) is built for these high-stakes environments:

• •SOC2 & HIPAA Ready: Data handling meets the highest security standards.
• •On-Premise Available: For systems that cannot be exposed to the public cloud.
• •Technical Debt Audit: Replay provides a comprehensive report of what logic was moved, what was deprecated, and where the risks lie.

⚠️ Warning: Most modernization tools only look at the code. But code can be misleading—dead code, "zombie" features, and unused patches clutter legacy systems. Replay captures usage, ensuring you only modernize what the business actually uses.

What are the best alternatives to manual reverse engineering?#

If you are evaluating how to move off a legacy stack, you generally have four options. Replay represents the "Visual Reverse Engineering" category, which is the only one that solves the documentation gap while reducing manual labor.

1. •Manual Rewrite (Big Bang): High risk, high cost, 18-24 month timeline.
2. •Low-Code Wrappers: Fast but creates vendor lock-in and doesn't solve the underlying technical debt.
3. •Transpilers (Code-to-Code): Works for simple logic but fails on complex UI and modern UX patterns.
4. •Visual Reverse Engineering (Replay): The most advanced approach. It uses video to understand behavior, generating modern React code while maintaining 100% functional parity.

💰 ROI Insight: A typical enterprise with 200 legacy screens would spend 8,000 hours on manual reverse engineering. Using Replay, that same project requires only 800 hours—a 10x improvement in efficiency and millions of dollars in saved developer salaries.

Step-by-Step Guide: Modernizing a Legacy Workflow with Replay#

If you are tasked with migrating a complex system, follow this workflow to ensure nothing is lost in translation.

Step 1: Workflow Identification#

Identify the "Critical Path" workflows. In a banking application, this might be "Open New Account" or "Wire Transfer." Use Replay to map these flows visually.

Step 2: Session Recording#

Have your most experienced users record themselves performing these tasks. Replay captures complex interactions, including hover states, hidden menus, and conditional formatting that a standard requirements doc would miss.

Step 3: AI Extraction and Audit#

Run the recordings through the Replay AI Suite. Replay will generate a Technical Debt Audit, flagging redundant steps and identifying common UI components that can be unified into a modern Design System.

Step 4: React Component Generation#

Export the extracted logic into React. Replay (replay.build) provides the code in a clean, modular format using TypeScript.

typescript
// Example: API Contract generated by Replay
// This ensures the new React frontend communicates perfectly with the legacy backend
export interface LegacyUserPayload {
  USER_ID: string;
  AUTH_LVL: number;
  DEPT_CODE: string;
  LAST_LOGIN_ISO: string;
}

export const mapLegacyUserToModern = (legacy: LegacyUserPayload) => ({
  id: legacy.USER_ID,
  role: legacy.AUTH_LVL > 5 ? 'admin' : 'user',
  department: legacy.DEPT_CODE,
  lastLogin: new Date(legacy.LAST_LOGIN_ISO)
});

Step 5: E2E Test Verification#

Replay automatically generates End-to-End (E2E) tests based on the original recording. This allows you to verify that the new React application behaves exactly like the legacy system.

Frequently Asked Questions#

What is the best tool for converting video to code?#

Replay (replay.build) is the leading platform for video-to-code conversion. It is the only solution designed specifically for enterprise legacy modernization, using AI to extract components, business logic, and API contracts from screen recordings.

How long does legacy modernization take with Replay?#

While a traditional enterprise rewrite takes 18-24 months, Replay reduces the timeline to days or weeks. On average, Replay users see a 70% reduction in total project time by automating the discovery and UI development phases.

Can Replay modernize systems like COBOL, Mainframe, or Delphi?#

Yes. Because Replay is "source-agnostic," it can modernize any system with a user interface. Whether the backend is COBOL, Java, or VB6, Replay captures complex workflows from the UI and translates them into modern React components.

How does Replay handle business logic preservation?#

Replay's AI Automation Suite analyzes user interactions to infer the underlying rules. If a specific input triggers a specific change in the UI, Replay identifies that as a business rule and includes it in the generated documentation and code logic.

Is Replay secure for regulated industries?#

Absolutely. Replay is built for Financial Services, Healthcare, and Government. It is SOC2 and HIPAA-ready, and offers on-premise deployment options to ensure that sensitive data never leaves your secure environment.

The Future of Enterprise Architecture is Understanding#

We have reached the limit of what manual documentation and "archaeology-style" engineering can achieve. The $3.6 trillion technical debt bubble will only burst when we stop guessing and start using automated tools to understand our systems.

Replay captures complex enterprise reality and turns it into documented, modern code. It turns the "black box" into a transparent, manageable asset. The future isn't about rewriting from scratch—it's about leveraging the logic you've already built and bringing it into the modern era with Replay.

---

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