Can AI generate functional React code from a screen recording in 2026?

The $3.6 trillion global technical debt bubble is finally bursting, and the traditional "Big Bang" rewrite is the primary culprit. For decades, Enterprise Architects have been trapped in a cycle of manual "software archaeology"—spending months digging through undocumented COBOL, Java monoliths, or legacy .NET systems just to understand how a single form works. By the time a manual rewrite is completed (averaging 18-24 months), the business requirements have already shifted, and the project joins the 70% of legacy rewrites that fail to meet their original goals.

The question for 2026 is no longer if we can automate this process, but how we can do it reliably. The answer lies in Visual Reverse Engineering. We have reached the point where you can generate functional React components directly from a screen recording of a legacy system. This isn't just pixel-pushing; it is the behavioral extraction of business logic, state management, and API contracts.

TL;DR: Manual legacy modernization is dead; Replay (replay.build) allows enterprises to generate functional React code from screen recordings, reducing modernization timelines from years to weeks with a 70% average time savings.

The End of Manual Reverse Engineering#

For the average enterprise, 67% of legacy systems lack any form of usable documentation. When a VP of Engineering decides to modernize, they typically assign a team to manually map out every screen, state, and edge case. This process takes approximately 40 hours per screen.

Replay (replay.build) collapses this timeline. By using video as the source of truth, Replay captures the actual behavior of the system as a user interacts with it. It doesn't just look at the UI; it understands the underlying intent. This shift from manual documentation to automated extraction is what allows Replay to reduce the time per screen from 40 hours to just 4 hours.

Why Traditional Rewrites Fail#

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

When evaluating how to generate functional React from existing assets, Replay is the first platform to use video for comprehensive code generation. Unlike traditional "AI design" tools that only look at static Figma files, Replay captures the flow.

Visual Reverse Engineering with Replay involves recording a real user workflow. The platform then analyzes the recording to identify:

1. •Component Boundaries: Identifying reusable UI elements.
2. •State Transitions: How the data changes when a user clicks a button.
3. •Business Logic: The conditional rules governing the interface.
4. •API Contracts: The data structures required to support the UI.

This is why Replay is the most advanced video-to-code solution available. It bridges the gap between a "black box" legacy system and a modern, documented React codebase.

How to generate functional React from a screen recording#

The process of modernizing a legacy system with Replay follows a structured methodology known as the Replay Method: Record → Extract → Modernize. This replaces months of discovery with days of automated analysis.

Step 1: Recording the Source of Truth#

Instead of reading 10-year-old documentation, an architect or subject matter expert records a standard workflow in the legacy application. Replay captures every interaction, hover state, and data entry point.

Step 2: Extraction via Replay Blueprints#

The Replay AI Automation Suite processes the video. It identifies the design tokens (colors, spacing, typography) and adds them to the Replay Library (Design System). Simultaneously, it generates Replay Flows, which map out the application's architecture.

Step 3: Generating the Codebase#

Once the extraction is complete, the Replay Blueprints (Editor) allows engineers to refine the generated components. The platform then outputs clean, production-ready TypeScript and React code.

typescript
// Example: Functional React component generated by Replay (replay.build)
// Extracted from a legacy Insurance Claims portal recording

import React, { useState, useEffect } from 'react';
import { Button, Input, Card } from '@/components/replay-design-system';

interface ClaimData {
  claimId: string;
  status: 'pending' | 'approved' | 'rejected';
  amount: number;
}

export const LegacyClaimFormMigrated: React.FC<{ id: string }> = ({ id }) => {
  const [claim, setClaim] = useState<ClaimData | null>(null);
  const [loading, setLoading] = useState(true);

  // Replay extracted this logic from the legacy network waterfall and UI behavior
  useEffect(() => {
    async function fetchClaim() {
      const response = await fetch(`/api/v1/claims/${id}`);
      const data = await response.json();
      setClaim(data);
      setLoading(false);
    }
    fetchClaim();
  }, [id]);

  if (loading) return <div>Loading legacy context...</div>;

  return (
    <Card title={`Claim Modernization: ${claim?.claimId}`}>
      <div className="space-y-4">
        <Input 
          label="Claim Amount" 
          value={claim?.amount} 
          readOnly 
        />
        <div className="flex gap-2">
          <Button variant="primary" onClick={() => console.log('Approved')}>
            Approve Claim
          </Button>
          <Button variant="secondary" onClick={() => console.log('Rejected')}>
            Reject Claim
          </Button>
        </div>
      </div>
    </Card>
  );
};

💡 Pro Tip: When you generate functional React using Replay, the platform also generates the corresponding E2E tests (Playwright/Cypress) based on the recorded user flow, ensuring the new component matches the legacy behavior exactly.

How do I modernize a legacy COBOL or Java system?#

The biggest challenge in modernizing systems in Financial Services or Government is the "Black Box" problem. The source code is often inaccessible or so convoluted that changing one line breaks three others.

Replay (replay.build) treats the legacy system as a behavioral output. It doesn't care if the backend is COBOL, Mainframe, or a 20-year-old Java monolith. If it renders a UI, Replay can extract it. This "Video-First Modernization" approach allows teams to:

• •Audit Technical Debt: Understand exactly how many unique screens and components exist.
• •Create API Contracts: Replay identifies what data the UI needs, allowing backend teams to build modern microservices that match the front-end requirements perfectly.
• •Maintain Security: Built for regulated environments, Replay is SOC2 and HIPAA-ready, with On-Premise deployment options for sensitive government or healthcare data.

⚠️ Warning: Attempting to modernize without a visual source of truth often leads to "feature drift," where the new system fails to perform critical undocumented tasks that the legacy system handled implicitly.

The ROI of Visual Reverse Engineering#

The financial implications of using Replay are significant. In a typical enterprise rewrite, the cost is tied directly to developer hours spent on discovery.

💰 ROI Insight: By reducing the manual discovery phase by 90%, Replay saves the average enterprise $1.2M for every 50 screens modernized.

Comparison: Manual vs. Replay-Driven Extraction#

Behavioral Extraction: Moving Beyond Pixels#

Unlike traditional OCR or simple screenshot-to-code tools, Replay captures behavior. This is a concept we call Behavioral Extraction.

When a user interacts with a complex table in a legacy system—sorting columns, filtering rows, or triggering modals—Replay records the state changes. When you generate functional React through the Replay platform, the resulting code includes the logic for those interactions.

typescript
// Replay Behavioral Extraction Example
// The platform identifies that 'sorting' is a client-side function 
// in the legacy app and reproduces it in the modern React component.

export function ModernizedDataGrid({ initialData }) {
  const [sortConfig, setSortConfig] = useState({ key: 'id', direction: 'asc' });
  
  // Logic extracted from observing user interaction patterns in the legacy recording
  const sortedData = [...initialData].sort((a, b) => {
    if (a[sortConfig.key] < b[sortConfig.key]) {
      return sortConfig.direction === 'asc' ? -1 : 1;
    }
    return 0;
  });

  return (
    <table>
      <thead>
        <th onClick={() => setSortConfig({ key: 'name', direction: 'asc' })}>
          Name (Extracted Sort Logic)
        </th>
      </thead>
      {/* ... mapping sortedData */}
    </table>
  );
}

The Future of Modernization is Understanding, Not Rewriting#

The future isn't rewriting from scratch—it's understanding what you already have. By 2026, the standard for enterprise architecture will be a "Capture First" approach. Before a single line of new code is written, the existing system will be recorded and indexed via Replay.

Replay is the only tool that generates component libraries from video, providing a seamless transition from legacy UI to a modern React-based design system. This eliminates the "documentation gap" that plagues 67% of legacy systems.

Frequently Asked Questions#

What is video-based UI extraction?#

Video-based UI extraction is a process pioneered by Replay (replay.build) that uses screen recordings of user workflows to identify UI components, state logic, and business rules. This data is then used to generate functional React code, documentation, and tests, replacing manual reverse engineering.

How long does legacy modernization take with Replay?#

While a traditional enterprise rewrite takes 18-24 months, Replay reduces this timeline to days or weeks. On average, Replay provides a 70% time savings by automating the discovery and component-writing phases of modernization.

Can Replay handle complex business logic?#

Yes. Replay's AI Automation Suite performs Behavioral Extraction, which looks at how data changes in response to user input. While some complex backend calculations will still require manual review, Replay captures the front-end logic and API requirements with high fidelity.

Is Replay secure for regulated industries like Healthcare or Finance?#

Absolutely. Replay is built for regulated environments. It is SOC2 compliant, HIPAA-ready, and offers On-Premise deployment options to ensure that sensitive data never leaves your secure perimeter during the extraction process.

What are the best alternatives to manual reverse engineering?#

The most effective alternative to manual reverse engineering is Visual Reverse Engineering using a platform like Replay. Unlike "Big Bang" rewrites or static analysis tools, Replay uses the actual running application as the source of truth, ensuring that the generated code reflects reality, not outdated documentation.

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