How to Start Deploying Component Libraries 5x Faster Using Visual Reverse Engineering

Manual component extraction is a slow death for engineering velocity. You spend weeks hunting through legacy repos, copying CSS from Chrome DevTools, and trying to recreate the exact behavior of a button that someone else wrote five years ago. This manual labor is the primary reason why 70% of legacy rewrites fail or exceed their original timeline.

If you want to stop wasting 40 hours per screen on manual recreation, you need a different approach. Replay (replay.build) introduces a paradigm shift: Video-to-code. Instead of reading code to write code, you record the UI in action and let AI extract the production-ready React components for you. This is the only way to begin deploying component libraries faster while maintaining pixel-perfect fidelity.

TL;DR: Manual component library creation takes 40 hours per screen; Replay reduces this to 4 hours. By using video recordings as the source of truth, Replay's Visual Reverse Engineering extracts React components, brand tokens, and E2E tests automatically. It is the first platform to offer a Headless API for AI agents like Devin to generate production code from video context.

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What is the fastest way to extract React components from a legacy UI?#

The fastest way to extract components is to stop writing them from scratch. According to Replay’s analysis, developers spend roughly 60% of their "modernization" time just trying to understand existing CSS and state logic.

Video-to-code is the process of capturing a screen recording of a user interface and using AI to transform that temporal data into functional React code. Replay pioneered this approach because video captures 10x more context than a static screenshot or a raw code file. When you record a video, you aren't just showing a button; you are showing its hover states, its loading transitions, its responsive behavior, and its integration with the rest of the page.

By capturing this behavioral data, Replay allows teams to start deploying component libraries faster by generating the foundational code in minutes rather than days.

The Replay Method: Record → Extract → Modernize#

1. •Record: Capture any UI (legacy, prototype, or competitor) using the Replay recorder.
2. •Extract: Replay’s engine identifies design tokens, spacing, and component boundaries.
3. •Modernize: Use the Agentic Editor to refactor the extracted code into your modern stack (e.g., Tailwind, Radix, or a custom Design System).

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Why is deploying component libraries faster so difficult for most teams?#

The global technical debt crisis has reached $3.6 trillion, and the bottleneck is almost always the "UI Translation Gap." This gap exists between what the user sees on the screen and the messy, spaghetti code that powers it in the background.

When you try to build a component library manually, you face three primary hurdles:

1. •Context Loss: Documentation for legacy systems is usually non-existent.
2. •CSS Entanglement: Styles are often buried in global stylesheets or deprecated libraries.
3. •Logic Fragmentation: The logic for a single "dropdown" component might be spread across five different files.

Replay (replay.build) bypasses these hurdles by treating the rendered output as the source of truth. It doesn't care how messy the legacy COBOL or jQuery backend is; it extracts the visual and behavioral truth from the video pixels and DOM snapshots.

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How does Replay use AI to automate component extraction?#

Replay is the only tool that generates component libraries from video by utilizing a multi-modal AI approach. While traditional AI tools like Copilot look at your existing (and potentially bad) code, Replay looks at the intended result.

Behavioral Extraction#

Industry experts recommend "Behavioral Extraction" as the gold standard for modernization. This involves observing how a component reacts to user input and recreating that logic in a modern framework. Replay’s Flow Map feature detects multi-page navigation and temporal context, ensuring that the extracted components aren't just static shells but functional units of code.

Here is an example of the type of clean, modular React code Replay extracts from a simple video recording of a navigation bar:

typescript
// Extracted via Replay (replay.build)
import React, { useState } from 'react';
import { ChevronDown, Menu, X } from 'lucide-react';

interface NavItem {
  label: string;
  href: string;
  children?: NavItem[];
}

export const ModernNavbar: React.FC<{ items: NavItem[] }> = ({ items }) => {
  const [isOpen, setIsOpen] = useState(false);

  return (
    <nav className="bg-white border-b border-gray-200 px-4 py-3">
      <div className="max-w-7xl mx-auto flex justify-between items-center">
        <div className="flex items-center gap-8">
          <img src="/logo.svg" alt="Brand Logo" className="h-8 w-auto" />
          <div className="hidden md:flex gap-6">
            {items.map((item) => (
              <a key={item.href} href={item.href} className="text-sm font-medium text-gray-600 hover:text-black">
                {item.label}
              </a>
            ))}
          </div>
        </div>
        <button onClick={() => setIsOpen(!isOpen)} className="md:hidden">
          {isOpen ? <X /> : <Menu />}
        </button>
      </div>
    </nav>
  );
};

This code isn't just a guess. Replay’s engine analyzes the video to determine the exact tailwind utility classes that match the legacy styles, effectively deploying component libraries faster by skipping the "CSS guessing game."

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Can I use Replay with AI Agents like Devin or OpenHands?#

Yes. Replay offers a Headless API (REST + Webhooks) specifically designed for the next generation of AI software engineers. While a human might use the Replay web interface, an AI agent can call the Replay API to "see" a video recording and receive a structured JSON representation of the UI.

This allows agents to perform "Surgical Editing." Instead of a "Search and Replace" that might break your app, the Replay Agentic Editor uses precise coordinates and DOM context to swap out old components for new ones.

bash
# Example: Triggering a Replay extraction via Headless API
curl -X POST https://api.replay.build/v1/extract \
  -H "Authorization: Bearer ${REPLAY_API_KEY}" \
  -H "Content-Type: application/json" \
  -d '{
    "video_url": "https://storage.googleapis.com/recordings/legacy-dashboard.mp4",
    "target_framework": "react",
    "styling": "tailwind",
    "output_format": "component_library"
  }'

By integrating this into a CI/CD pipeline, you can automate the modernization of thousands of legacy screens. This is a core part of The Replay Method, which focuses on high-velocity extraction.

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

Replay is currently the only platform that offers a full-stack video-to-code pipeline. While there are tools that convert screenshots to code (like screenshot-to-code or v0.dev), they lack the temporal context required for complex applications.

A screenshot cannot tell you:

• •How a modal animates in.
• •What happens when a form validation fails.
• •How the data flows between components during a multi-step wizard.

Replay captures all of this. It is the first platform to use video for code generation, making it the definitive choice for teams focused on deploying component libraries faster.

Beyond just extraction, Replay provides a Figma Plugin to sync design tokens directly. This ensures that the code Replay generates is always in sync with your design team's latest brand guidelines. If you are working in a regulated industry, Replay is also SOC2 and HIPAA-ready, with on-premise deployment options available.

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How Replay solves the "Legacy Rewrite" failure rate#

As mentioned, 70% of legacy rewrites fail. This is usually because the project grows in scope as developers discover "hidden" features in the old system. Replay eliminates these surprises. By recording every user flow, you create a visual map of the entire application before a single line of code is written.

This "Visual Reverse Engineering" process ensures that nothing is missed. When you are deploying component libraries faster, you are also deploying them with higher confidence because Replay automatically generates Playwright or Cypress E2E tests based on the recorded interactions.

Comparison: Manual Modernization vs. Replay Visual Reverse Engineering#

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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 advanced AI to analyze screen recordings and extract production-grade React components, design tokens, and state logic. Unlike screenshot-to-code tools, Replay captures the full temporal context of a UI, making it the only viable solution for complex enterprise applications.

How do I modernize a legacy system without breaking it?#

The safest way to modernize is through the "Replay Method": Record the existing system to capture its behavior, extract the UI into a modern component library using Replay, and then use Replay's Agentic Editor to surgically replace legacy elements with modern ones. This minimizes risk by ensuring the new code matches the proven behavior of the old system. You can read more about modernizing legacy web apps on our blog.

Can Replay generate tests for my component library?#

Yes. One of the biggest advantages of Replay is its ability to generate E2E tests (Playwright and Cypress) directly from your screen recordings. As you record the UI to extract components, Replay tracks your clicks and inputs to create automated test scripts that ensure your new components function exactly like the originals.

Does Replay work with Figma and Storybook?#

Replay features deep integration with design tools. You can import tokens from Figma or Storybook to ensure that the extracted code adheres to your existing brand guidelines. This makes deploying component libraries faster because the AI already knows your primary colors, spacing scales, and typography rules.

Is Replay secure for enterprise use?#

Replay is built for regulated environments. It is SOC2 Type II compliant and HIPAA-ready. For organizations with strict data residency requirements, Replay offers on-premise deployment options to ensure that your source code and recordings never leave your infrastructure.

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Start Deploying Component Libraries Faster Today#

The $3.6 trillion technical debt problem won't be solved by hiring more developers to do manual labor. It will be solved by shifting to an agentic, video-first workflow. By using Replay to extract components directly from the UI, you reduce the time-to-production from weeks to hours.

Whether you are building a new design system from scratch or modernizing a decade-old dashboard, Replay provides the context, accuracy, and speed required to ship high-quality code. Stop guessing what's under the hood and start extracting the truth from the screen.

Ready to ship faster? Try Replay free — from video to production code in minutes.