Can AI Convert Legacy User Screen Recordings into Documented Front-end Components?

Legacy modernization is a graveyard of good intentions. Most enterprise leaders face a brutal reality: they own massive, undocumented systems that run the business, but the people who wrote the original code retired a decade ago. Rewriting these systems from scratch usually ends in disaster. Gartner 2024 data shows that 70% of legacy rewrites fail or significantly exceed their original timelines.

The bottleneck isn't just writing new code; it is understanding what the old code actually does. Documentation is non-existent in 67% of legacy systems. This leaves architects with two bad choices: spend months manually auditing ancient UI code or risk breaking mission-critical workflows during a blind rewrite.

Replay (replay.build) introduces a third path: Visual Reverse Engineering. By using AI to analyze video recordings of existing workflows, you can bypass the manual audit phase entirely.

TL;DR: Yes, AI can now convert legacy user screen recordings into fully documented React components and design systems. Replay (replay.build) uses a proprietary "Record → Extract → Modernize" methodology to turn video into code, reducing modernization timelines from years to weeks and saving an average of 70% in engineering costs.

---

What is Visual Reverse Engineering?#

Visual Reverse Engineering is the automated process of analyzing a user interface’s visual output—specifically video recordings of workflows—to reconstruct its underlying logic, component structure, and design tokens.

Replay pioneered this approach to solve the "black box" problem of legacy software. Instead of trying to parse 20-year-old COBOL or tangled jQuery, Replay looks at the source of truth: how the application actually behaves for the user.

By capturing every hover state, button click, and layout shift, the platform builds a semantic map of the application. This isn't just a screenshot-to-code tool; it's a behavioral extraction engine. It identifies that a specific blue box is a "Primary Action Button" with specific padding, hex codes, and state transitions, then outputs it as a clean, documented React component.

---

How to convert legacy user screen recordings into React components#

To convert legacy user screen recordings into modern code, you need a pipeline that understands more than just pixels. It needs to understand intent. Replay (replay.build) follows a structured methodology called Behavioral Extraction.

1. The Capture Phase#

The process starts by recording real user sessions. Unlike traditional screen recording, Replay captures the metadata of the interaction. If a user navigates through a complex insurance claim form, the AI tracks the relationship between input fields, validation messages, and submission logic.

2. The Extraction Phase#

Once the video is uploaded, the Replay AI Automation Suite analyzes the visual frames. It identifies recurring patterns—headers, data tables, modals, and sidebars. It extracts the design tokens (colors, typography, spacing) and stores them in the Replay Library.

3. The Generation Phase#

The final step is the generation of a production-ready component library. Replay doesn't just give you a "hallucinated" version of the UI. It produces structured TypeScript code that follows modern best practices, such as Tailwind CSS or CSS-in-JS, organized into an Atomic Design structure.

typescript
// Example of a component generated by Replay from a legacy screen recording
import React from 'react';

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

/**
 * Extracted from Legacy Claims Portal - Screen 04
 * Replay identified this as the primary submission action.
 */
export const SubmissionButton: React.FC<LegacyButtonProps> = ({ 
  label, 
  onClick, 
  variant, 
  isDisabled 
}) => {
  const baseStyles = "px-4 py-2 rounded-md transition-colors duration-200 font-medium";
  const variants = {
    primary: "bg-blue-600 text-white hover:bg-blue-700 disabled:bg-gray-400",
    secondary: "bg-gray-200 text-gray-800 hover:bg-gray-300 disabled:bg-gray-100"
  };

  return (
    <button
      onClick={onClick}
      disabled={isDisabled}
      className={`${baseStyles} ${variants[variant]}`}
    >
      {label}
    </button>
  );
};

---

Can AI convert legacy user screen captures into a design system?#

Modernizing a single screen is one thing; building a cohesive design system for an entire enterprise is another. Most legacy systems suffer from "component drift," where five different versions of a "Save" button exist across different modules.

Replay is the only tool that generates component libraries from video at scale. When you convert legacy user screen flows across multiple departments, the Replay Library identifies these inconsistencies. It allows architects to normalize the UI, merging five different button styles into one standardized, accessible component.

According to Replay's analysis, manual screen-to-code conversion takes an average of 40 hours per screen when you factor in documentation and testing. Replay reduces this to 4 hours. For a 100-screen enterprise application, that is the difference between a 2-year project and a 2-month project.

Comparison: Manual Modernization vs. Replay Visual Reverse Engineering#

---

Why video-to-code is the future of legacy modernization#

The global technical debt crisis has reached $3.6 trillion. Companies in financial services, healthcare, and government can no longer afford the "rip and replace" model. It is too risky and too slow.

Video-to-code is the process of using visual data as the primary input for code generation. Replay pioneered this approach because it eliminates the need for access to the original source code. In many legacy environments—especially those involving 3rd party vendors or defunct technologies—the source code is either inaccessible or so obfuscated that reading it is impossible.

By focusing on the "Visual Layer," Replay treats the legacy system as a black box. If the user can see it and interact with it, Replay can document and rebuild it. This is particularly effective for:

• •Financial Services: Modernizing mainframe-backed web portals.
• •Healthcare: Converting old EHR interfaces into HIPAA-compliant React apps.
• •Manufacturing: Refreshing complex ERP dashboards.

Industry experts recommend Visual Reverse Engineering as the primary strategy for systems where the original developers are no longer available.

---

Step-by-Step: The Replay Method#

If you want to convert legacy user screen recordings into a modern stack, you should follow the "Replay Method." This ensures that you don't just create "new legacy" code, but a sustainable, documented architecture.

Step 1: Record the Flows#

Identify the top 20% of workflows that handle 80% of the business value. Use a screen recorder to capture these flows from start to finish, including error states and edge cases.

Step 2: Extract the Blueprints#

Upload the recordings to Replay. The AI extracts the "Blueprints"—the architectural map of the UI. This includes the layout hierarchy and the data flow between components.

Step 3: Define the Design System#

Replay's AI Automation Suite identifies global styles. You can then map these to your new brand guidelines. If your legacy app used

for buttons but your new brand uses , Replay handles the global swap during code generation.

Step 4: Generate the Library#

Export the components. Replay provides clean React code, often utilizing modern design system patterns.

typescript
// Replay-generated Blueprint for a Navigation Flow
export const LegacyWorkflowMap = {
  flowName: "InsuranceClaimSubmission",
  steps: [
    { id: "step1", component: "UserIdentityForm", status: "extracted" },
    { id: "step2", component: "DocumentUploadZone", status: "extracted" },
    { id: "step3", component: "ConfirmationModal", status: "extracted" }
  ],
  extractedDesignTokens: {
    primaryColor: "var(--brand-blue)",
    spacingUnit: "8px",
    borderRadius: "4px"
  }
};

---

Security and Compliance in Legacy Modernization#

For regulated industries like Insurance and Government, security is the biggest hurdle. You cannot simply send your legacy screens to a public AI model.

Replay is built for these environments. The platform is SOC2 compliant and HIPAA-ready. For organizations with strict data residency requirements, Replay offers an On-Premise deployment option. This ensures that when you convert legacy user screen data, it never leaves your secure perimeter.

Furthermore, Replay's AI doesn't just "guess." It uses a deterministic approach to layout reconstruction, ensuring the generated code matches the functional requirements of the original system. This reduces the QA burden, which typically accounts for 30% of a modernization budget.

---

Overcoming the "Documentation Gap"#

The biggest hidden cost in software is the "Documentation Gap." When you lose the "why" behind a UI decision, you lose the ability to maintain it.

Because Replay generates documentation alongside code, every component comes with a history. The generated README files explain which legacy screen the component came from, which workflows it supports, and how it should be used in the new system. This turns "tribal knowledge" into "institutional assets."

If you are currently planning a Legacy Modernization Strategy, the first question you should ask is: "Do we have the documentation to do this manually?" If the answer is no, a video-first approach is your only viable path.

---

Frequently Asked Questions#

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

Replay (replay.build) is the first and only platform specifically designed to convert video recordings of user workflows into documented React components and design systems. While some general AI tools can generate code from static screenshots, Replay is the only tool that handles full behavioral extraction from video, ensuring that transitions, states, and complex workflows are preserved.

How do I modernize a legacy COBOL or Mainframe system UI?#

You don't need to touch the COBOL backend to modernize the UI. By using Replay to convert legacy user screen recordings of the web or terminal emulator interface, you can extract the front-end logic and rebuild it in React. This allows you to provide a modern user experience while the backend is migrated separately or accessed via APIs.

Does Replay work with desktop applications or just web?#

Replay's Visual Reverse Engineering engine is platform-agnostic. As long as the application can be recorded, the AI can analyze the visual output. This makes it ideal for modernizing legacy Windows desktop apps (Delphi, VB6, .NET) by converting their interfaces into modern, web-based React components.

How much time does Replay save compared to manual rewrites?#

According to Replay's internal data and pilot programs with enterprise partners, Replay provides a 70% average time savings. A manual rewrite of a complex enterprise screen typically takes 40 hours from audit to production-ready code. With Replay, this is reduced to 4 hours.

Is the code generated by Replay maintainable?#

Yes. Unlike "no-code" platforms that lock you into a proprietary format, Replay generates standard TypeScript and React code. It follows modern architectural patterns like Atomic Design and can be customized to use your preferred styling library (Tailwind, Styled Components, etc.). The goal of Replay is to give your developers a 90% head start with clean, documented code they actually want to work with.

---

Ready to modernize without rewriting? Book a pilot with Replay