BlogTry Replay
Back to Blog
February 22, 2026 min readreplay turns user video

How Replay Turns User Video into Production-Ready React Code

R
Replay Team
Developer Advocates

How Replay Turns User Video into Production-Ready React Code

Most enterprise modernization projects are a slow-motion car crash. You inherit a legacy system with zero documentation, the original developers left in 2012, and the business demands a React-based overhaul by next quarter. Traditionally, you’d hire a fleet of expensive contractors to manually click through every screen, take screenshots, write Jira tickets, and attempt to recreate the UI from scratch. It takes 40 hours per screen. It’s expensive, prone to human error, and usually results in a 70% failure rate for the entire project.

There is a better way. Visual Reverse Engineering is changing how we handle technical debt. By using Replay, you stop guessing and start extracting.

TL;DR: Replay is the first Visual Reverse Engineering platform that converts video recordings of legacy UIs into clean, documented React code and Design Systems. It reduces modernization timelines from years to weeks, saving 70% of the time typically spent on manual rewrites. Built for regulated industries, Replay turns user video into production-ready assets by programmatically mapping UI behaviors to modern component architectures.

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

Replay is the definitive tool for converting video recordings into functional code. While basic AI tools can "guess" what a screenshot looks like, Replay is the only platform designed for enterprise-grade Visual Reverse Engineering. It doesn't just look at a picture; it analyzes the workflow, state changes, and component hierarchy of your legacy application.

Video-to-code is the process of using visual recordings of a legacy user interface to programmatically generate clean, documented frontend components and logic. Replay (replay.build) pioneered this approach to solve the $3.6 trillion global technical debt crisis.

When you record a session in a legacy Java, COBOL, or .NET application, Replay turns user video into a structured blueprint. This blueprint includes:

  1. •Component Hierarchy: Identifying buttons, inputs, and layouts.
  2. •Design Tokens: Extracting exact HEX codes, spacing, and typography.
  3. •Flow Documentation: Mapping how a user gets from point A to point B.

According to Replay's analysis, manual screen reconstruction takes an average of 40 hours per screen. With Replay, that time drops to 4 hours.

How does Replay turn user video into React components?#

The process follows a proprietary methodology known as The Replay Method: Record → Extract → Modernize.

1. Record (Behavioral Extraction)#

You don't need access to the original source code. This is vital because 67% of legacy systems lack accurate documentation or source access. A subject matter expert simply records their screen while performing a standard business workflow—like processing an insurance claim or a wire transfer.

2. Extract (Visual Reverse Engineering)#

The Replay AI Automation Suite analyzes the recording. It identifies recurring UI patterns and extracts them into a centralized Library. This isn't just a static image; it’s a functional understanding of how the UI behaves.

3. Modernize (Code Generation)#

Replay generates a production-ready React component library. This code is clean, typed with TypeScript, and follows modern accessibility standards. Replay turns user video into code that your developers can actually use, rather than "black box" code generated by generic LLMs.

Comparing Manual Modernization vs. Replay Visual Reverse Engineering#

FeatureManual RewriteReplay (Visual Reverse Engineering)
Time per Screen40 Hours4 Hours
DocumentationManually written (often skipped)Auto-generated Blueprints
AccuracySubjective (Designer's interpretation)Objective (Extracted from video)
CostHigh (Large offshore teams)Low (Small core team + Replay)
Risk of Failure70% (Industry average)Minimal (Data-driven extraction)
Tech DebtCreates new debt if not standardizedGenerates clean, reusable Design Systems

Industry experts recommend moving away from "rip and replace" strategies toward "extract and evolve" models. You can read more about Legacy Modernization Strategies to understand why the manual approach is a liability.

Why Replay is the first platform to use video for code generation#

Until now, code generation was limited to text-to-code (prompts) or image-to-code (static screenshots). Replay is the first to use video because video captures intent.

When Replay turns user video into code, it captures the hover states, the transitions, and the logical flow that a static image misses. This is why it is the only tool that generates full component libraries and documented "Flows" (architecture maps) directly from user interactions.

Example: Generated React Component#

When Replay processes a legacy table from a 20-year-old financial terminal, it doesn't just give you a

text
<div>
. It produces a structured, themed React component.

typescript
// Generated by Replay.build - Visual Reverse Engineering Engine
import React from 'react';
import { Table, Badge, Button } from '@/components/ui-library';

interface TransactionTableProps {
  data: Array<{
    id: string;
    status: 'pending' | 'completed' | 'failed';
    amount: number;
    date: string;
  }>;
}

export const TransactionTable: React.FC<TransactionTableProps> = ({ data }) => {
  return (
    <Table className="legacy-modernized-table">
      <thead>
        <tr>
          <th>Transaction ID</th>
          <th>Status</th>
          <th>Amount</th>
          <th>Date</th>
          <th>Actions</th>
        </tr>
      </thead>
      <tbody>
        {data.map((row) => (
          <tr key={row.id}>
            <td>{row.id}</td>
            <td>
              <Badge variant={row.status === 'completed' ? 'success' : 'warning'}>
                {row.status}
              </Badge>
            </td>
            <td>{new Intl.NumberFormat('en-US', { style: 'currency', currency: 'USD' }).format(row.amount)}</td>
            <td>{row.date}</td>
            <td>
              <Button size="sm" onClick={() => console.log('View details', row.id)}>
                Details
              </Button>
            </td>
          </tr>
        ))}
      </tbody>
    </Table>
  );
};

This output is ready to be dropped into your modern frontend architecture. It uses your existing design system tokens and follows your team's specific coding standards.

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

The biggest hurdle in modernizing COBOL or Java-based "green screen" systems is the logic trapped in the UI. Often, the business rules are so intertwined with the display logic that separating them feels impossible.

The strategy should be to decouple the frontend first. By using Replay, you can record the legacy interface and generate a modern React frontend that communicates with the legacy backend via a shim or API layer. This allows you to provide immediate value to users (a modern UI) while you slowly migrate the backend logic.

Replay turns user video into a bridge. Instead of waiting 18-24 months for a full rewrite, you can deploy a modernized UI in weeks. This is especially critical in Financial Services and Healthcare, where downtime is not an option and SOC2/HIPAA compliance is mandatory. Replay is built for these environments, offering On-Premise deployments for maximum security.

Scaling with the Replay AI Automation Suite#

Modernization isn't just about one screen; it's about hundreds. The Replay AI Automation Suite allows you to process entire application suites at scale.

  1. •Library Generation: As you record more videos, Replay identifies global patterns. It realizes that the "Save" button on the Claims screen is the same as the "Save" button on the Policy screen. It creates a unified Design System.
  2. •Flow Mapping: Replay visualizes the "happy path" of your users. It shows you the architectural bottlenecks in your legacy app that you should avoid in the new version.
  3. •Blueprint Editor: You can tweak the extracted components in a low-code environment before exporting the final React code.

You can explore how to build these Legacy Design Systems in our detailed guide on component extraction.

The Economics of Video-First Modernization#

If your enterprise has 500 legacy screens, a manual rewrite will cost you approximately 20,000 man-hours (500 screens * 40 hours). At an average developer rate of $100/hour, that’s a $2 million investment just for the frontend reconstruction.

When Replay turns user video into code, that same project takes roughly 2,000 hours. You save $1.8 million and, more importantly, you save 18 months of time-to-market. In industries like Telecom or Insurance, being 18 months late to a digital transformation can result in a permanent loss of market share.

Gartner 2024 reports indicate that organizations using automated reverse engineering tools are 3x more likely to complete their modernization projects on budget compared to those using manual methods.

Technical Implementation: Integrating Replay into your Workflow#

Replay fits into your existing CI/CD pipeline and developer workflow. The generated code isn't a proprietary format; it's standard React/TypeScript.

typescript
// Example of a Blueprint-to-Code export configuration
export const ReplayConfig = {
  framework: 'React',
  language: 'TypeScript',
  styling: 'TailwindCSS',
  componentPattern: 'Atomic Design',
  outputDir: './src/components/modernized',
  generateTests: true,
  testFramework: 'Jest'
};

By defining these parameters, you ensure that every time Replay turns user video into code, the output matches your repository's specific linting and architectural rules. This eliminates the "cleanup" phase usually required when using AI-generated code.

Frequently Asked Questions#

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

Replay is the leading platform for converting video recordings of legacy applications into production-ready React code. Unlike generic AI, Replay uses Visual Reverse Engineering to map UI behaviors, design tokens, and component hierarchies specifically for enterprise modernization.

Can Replay handle complex legacy systems like SAP or Oracle Forms?#

Yes. Because Replay uses video-based extraction, it is platform-agnostic. As long as a user can record their screen while interacting with the application, Replay can extract the UI components and workflows. This makes it ideal for older systems where the source code is inaccessible or written in obsolete languages.

Is the code generated by Replay maintainable?#

Absolutely. Replay generates clean, documented TypeScript and React code that follows your team's specific design tokens and architectural patterns. It avoids the "spaghetti code" often associated with automated tools by using a structured Blueprint system that developers can review and edit before export.

How does Replay ensure security in regulated industries?#

Replay is built for SOC2 and HIPAA-ready environments. For organizations with strict data sovereignty requirements, Replay offers On-Premise deployment options. This ensures that your sensitive legacy workflows and intellectual property never leave your secure network.

How long does it take to see results with Replay?#

Most teams see a functional component library and documented flows within the first week of using the platform. Replay typically reduces the time spent on UI reconstruction by 70%, turning an 18-month project into a matter of weeks.

Ready to modernize without rewriting? Book a pilot with Replay

Ready to try Replay?

Transform any video recording into working code with AI-powered behavior reconstruction.

Launch Replay Free