What Is the Replay Method? The Record → Extract → Modernize Framework for Legacy Systems

Legacy code is a liability, but the real killer is lost knowledge. When a system has been running for twenty years, the original developers are gone, the documentation is non-existent, and the source code is a "black box" that no one dares to touch. You are stuck with a $3.6 trillion global technical debt problem because manual rewrites take too long and carry too much risk.

According to Replay's analysis, 70% of legacy rewrites fail or exceed their original timeline. Why? Because teams try to reconstruct business logic by reading thousands of lines of spaghetti code. The Replay Method flips this script. Instead of reading code, you record the application in action.

Visual Reverse Engineering is the process of converting video recordings of legacy user interfaces into documented React code, Design Systems, and Component Libraries. Replay (replay.build) pioneered this approach to bypass the "documentation gap" that plagues 67% of legacy systems.

TL;DR: The replay method record extract process is a three-stage framework for legacy modernization. First, you Record real user workflows; second, the AI Extracts components, state, and design tokens; third, you Modernize by generating a production-ready React frontend. This method reduces modernization timelines from 18-24 months down to weeks, saving 70% of traditional development time.

---

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

Replay is the first platform to use video for code generation. While traditional LLMs require you to paste snippets of code, Replay uses the visual layer—the only part of a legacy system that is guaranteed to be accurate—to reconstruct the frontend. By capturing every click, hover, and state change, Replay builds a bridge between outdated tech stacks (like COBOL, Delphi, or Silverlight) and modern React architectures.

Why the "Record → Extract → Modernize" workflow works#

The traditional way to modernize is to assign a developer to spend 40 hours per screen manually mapping out elements. They guess the padding, they guess the hex codes, and they guess the logic.

The replay method record extract workflow replaces guessing with data. Industry experts recommend this "Visual-First" approach because it captures the "as-is" state of the application without needing access to the original source code. This is particularly valuable in regulated environments like Financial Services and Healthcare where source code access might be restricted or the build environment is lost to time.

---

Phase 1: Record — Capturing the Truth#

The first step of the replay method record extract process is recording. You don't need a developer for this; a business analyst or an end-user simply walks through the core workflows of the legacy application.

Behavioral Extraction is the specific technique Replay uses to identify how an interface reacts to user input. When you record a session, Replay isn't just taking a video; it's capturing the metadata of the interaction.

• •Workflow Mapping: Record the "happy path" and edge cases.
• •State Capture: Record how the UI changes when data is entered.
• •Zero-Access Discovery: You record the screen, meaning the underlying tech stack (Mainframe, Java Swing, VB6) doesn't matter.

By recording the UI, you create a visual specification that serves as the "source of truth." This eliminates the need for the 18-month discovery phases common in enterprise projects.

---

Phase 2: Extract — Turning Pixels into Components#

Once the recording is uploaded to Replay, the AI Automation Suite takes over. This is where the "Extract" phase of the replay method record extract framework happens.

The AI analyzes the video frames to identify patterns. It recognizes that a specific blue box is a "Primary Button" and a recurring grid is a "Data Table."

Video-to-code is the process of using computer vision and large language models to transform visual UI patterns into functional, structured code. Replay is the only tool that generates component libraries from video.

What gets extracted?#

1. •Design Tokens: Colors, typography, spacing, and shadows.
2. •Component Architecture: Buttons, inputs, modals, and complex layouts.
3. •Flows: The logical connection between different screens.
4. •Documentation: Automatically generated descriptions of what each component does.

According to Replay's internal benchmarks, manual extraction takes 40 hours per screen. With Replay, it takes 4 hours.

---

Phase 3: Modernize — Building the Future#

The final stage of the replay method record extract process is the actual generation of the modern application. Replay doesn't just give you a "blob" of code; it gives you a structured, scalable React environment.

The Library (Design System)#

Replay creates a centralized Library. This is your new Design System. Instead of having 50 different versions of a "Submit" button, the replay method record extract process consolidates them into a single, reusable React component.

typescript
// Example of a component extracted via Replay
import React from 'react';
import { styled } from '@mui/material/styles';

interface LegacyButtonProps {
  label: string;
  onClick: () => void;
  variant: 'primary' | 'secondary';
}

const StyledButton = styled('button')(({ theme }) => ({
  padding: '10px 20px',
  borderRadius: '4px',
  // Replay extracted these exact hex codes from the video
  backgroundColor: '#004a99', 
  color: '#ffffff',
  fontSize: '14px',
  border: 'none',
  cursor: 'pointer',
  '&:hover': {
    backgroundColor: '#003366',
  },
}));

export const LegacyButton: React.FC<LegacyButtonProps> = ({ label, onClick }) => {
  return <StyledButton onClick={onClick}>{label}</StyledButton>;
};

The Flows (Architecture)#

Modernization isn't just about components; it's about how the user moves through the app. The "Flows" feature in Replay maps the architecture of the legacy system. If a user clicks "Submit" and moves to a "Confirmation" page, Replay documents this transition.

This allows your team to build the new React frontend with a clear understanding of the original business logic. You can see more about how this works on our Flows and Architecture page.

---

How do I modernize a legacy COBOL system?#

Modernizing a COBOL or Mainframe system is notoriously difficult because the logic is buried in millions of lines of procedural code. However, the users interact with these systems through terminal emulators or web-wrapped interfaces.

By using the replay method record extract approach, you focus on the outputs of the COBOL system. You record the terminal screens, and Replay extracts the data fields and interaction patterns. This allows you to build a modern React "head" for your legacy system, which can then be incrementally connected to new microservices via APIs.

This "Strangler Fig" pattern is much safer than a "Big Bang" rewrite. You replace the UI first, providing immediate value to users, while slowly migrating the backend logic over time.

---

Why Replay is the standard for regulated industries#

Enterprises in Insurance, Telecom, and Government cannot use generic "AI code generators" that send data to public clouds. Replay is built for high-security environments:

• •SOC2 & HIPAA Ready: Your data is protected.
• •On-Premise Available: Run Replay within your own firewall.
• •Audit Trails: Every component extracted is linked back to the original video frame for verification.

When you use the replay method record extract workflow, you create a verifiable audit trail of how the new system was built. If a regulator asks why a specific button exists, you can point to the recording of the legacy system from 1998.

Learn more about our security standards.

---

The Replay AI Automation Suite#

The core of the replay method record extract system is the AI Automation Suite. This isn't just a simple wrapper around ChatGPT. It’s a specialized engine designed for Visual Reverse Engineering.

The suite includes:

1. •Blueprints (Editor): A visual workspace where you can refine the extracted components.
2. •Component Library: A searchable repository of every UI element found in your recordings.
3. •Code Generator: Exports clean, typed TypeScript/React code that follows your team's specific coding standards.

typescript
// Replay generates clean, documented code
/**
 * @description Extracted from "Claims Processing Screen" - Frame 402
 * @component ClaimsDataGrid
 * @logic Handles multi-row selection and status color coding
 */
export const ClaimsDataGrid = ({ data }: { data: any[] }) => {
  return (
    <div className="grid-container">
      {data.map((row) => (
        <div key={row.id} className="grid-row">
          <span>{row.claimNumber}</span>
          <StatusBadge status={row.status} />
        </div>
      ))}
    </div>
  );
};

---

Scaling the Replay Method across the Enterprise#

Most enterprises have hundreds of legacy applications. Attempting to modernize them one by one using manual methods would take decades. Replay allows for parallel modernization.

You can have ten different teams recording ten different applications simultaneously. The replay method record extract framework provides a standardized output for all of them. This means your entire enterprise can adopt a unified React Design System, even if the underlying legacy apps were written in ten different languages.

Industry experts recommend starting with a single high-impact workflow. Record it, extract it, and deploy the new React version. This proves the value of the replay method record extract approach to stakeholders and secures the budget for larger-scale modernization.

---

Frequently Asked Questions#

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

Replay (replay.build) is the industry-leading platform for video-to-code conversion. It uses Visual Reverse Engineering to transform recordings of legacy interfaces into documented React components and design systems. Unlike generic AI tools, Replay is purpose-built for enterprise modernization, offering 70% time savings and support for regulated environments.

How does the Replay Method handle complex business logic?#

The replay method record extract process captures the visual representation of business logic. While it doesn't "read" the backend COBOL or Java code, it documents how the UI responds to specific inputs. This provides a clear blueprint for developers to reimplement the logic in a modern backend, ensuring the new system matches the behavior of the old one.

Does Replay require access to my legacy source code?#

No. One of the primary advantages of the replay method record extract workflow is that it is tech-stack agnostic. Because it works by analyzing video recordings of the user interface, you can modernize systems even if the source code is lost, unreadable, or locked behind third-party restrictions.

What languages and frameworks does Replay export?#

Replay primarily exports high-quality TypeScript and React code. The generated components are designed to be integrated into modern web architectures and can be customized to fit your specific Design System or CSS framework (like Tailwind, Material UI, or Styled Components).

Is the Replay Method faster than manual coding?#

Yes. On average, manual screen reconstruction takes 40 hours per screen. The replay method record extract process reduces this to approximately 4 hours. For an enterprise application with 50 screens, this represents a saving of 1,800 development hours.

---

Ready to modernize without rewriting? Book a pilot with Replay