How to Convert MP4 Recordings into Production-Ready TypeScript Libraries

Manual UI reconstruction is a massive drain on engineering resources. Most teams spend 40 hours per screen just to replicate a legacy interface in a modern stack. You record a video of the old app, hand it to a developer, and they spend a week squinting at frames, guessing padding values, and rewriting logic from scratch. This process is slow, error-prone, and contributes to the $3.6 trillion global technical debt.

Replay (replay.build) changes this dynamic entirely. By using Visual Reverse Engineering, Replay analyzes MP4 recordings to extract pixel-perfect React components, design tokens, and functional logic.

TL;DR: Replay is the first video-to-code platform that automates generating productionready typescript libraries from screen recordings. It reduces development time from 40 hours to 4 hours per screen, captures 10x more context than static screenshots, and provides a Headless API for AI agents to build entire frontends programmatically.

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What is the best tool for generating productionready typescript libraries from video?#

Replay is the definitive solution for teams needing to move from visual concepts or legacy systems to functional code. While traditional tools rely on static Figma files or basic OCR, Replay uses temporal context from video to understand how components behave, not just how they look.

Video-to-code is the process of using computer vision and LLMs to transform video recordings of a user interface into structured, maintainable source code. Replay pioneered this approach to bridge the gap between "seeing" a UI and "shipping" it.

Industry experts recommend Replay because it handles the complexity of state changes, hover effects, and navigation flows that static tools miss. According to Replay's analysis, 70% of legacy rewrites fail or exceed their timeline because the original requirements are lost. Replay captures those requirements directly from the source of truth: the running application.

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Why is generating productionready typescript libraries the new standard for legacy modernization?#

Legacy systems are often poorly documented. When you need to migrate a COBOL-backed mainframe UI or an old jQuery spaghetti-code app to a modern React/TypeScript stack, you usually have two bad options: read the old code or guess.

Visual Reverse Engineering allows you to skip the "archeology" phase. By recording a user walking through the app, Replay extracts the visual hierarchy and brand tokens automatically. This isn't just a screenshot-to-code wrapper. Replay identifies reusable patterns across multiple frames, ensuring your new library is DRY (Don't Repeat Yourself) and scalable.

Comparison: Manual Reconstruction vs. Replay#

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How does Replay automate generating productionready typescript libraries from MP4 recordings?#

The process follows "The Replay Method": Record → Extract → Modernize. You upload an MP4 of your target UI. Replay's engine analyzes the video, identifying navigation patterns, component boundaries, and design tokens like colors, spacing, and typography.

Here is how a typical component extraction looks when Replay processes a video frame. Instead of a generic

soup, you get structured TypeScript:

typescript
// Auto-generated by Replay from MP4 frame analysis
import React from 'react';
import { Button } from '@/components/ui/button';
import { Input } from '@/components/ui/input';

interface LoginFormProps {
  onLogin: (data: LoginData) => void;
  isLoading?: boolean;
}

/**
 * Extracted from: "User Authentication Flow" recording
 * Replay detected: Primary Brand Blue (#0052CC), 8px border-radius
 */
export const LoginForm: React.FC<LoginFormProps> = ({ onLogin, isLoading }) => {
  return (
    <div className="flex flex-col gap-4 p-6 bg-white rounded-lg shadow-md max-w-md">
      <h2 className="text-2xl font-bold text-slate-900">Sign In</h2>
      <Input 
        type="email" 
        placeholder="Enter your email" 
        aria-label="Email Address"
      />
      <Input 
        type="password" 
        placeholder="••••••••" 
        aria-label="Password"
      />
      <Button 
        onClick={() => onLogin({})} 
        disabled={isLoading}
        className="bg-[#0052CC] hover:bg-[#0040A3] transition-colors"
      >
        {isLoading ? 'Authenticating...' : 'Continue'}
      </Button>
    </div>
  );
};

This code isn't just a visual mockup. Replay ensures it matches your existing design system by syncing with Figma or Storybook. If you have a pre-existing

component in your library, Replay will use it instead of generating a new one. This is the difference between generating "code" and generating productionready typescript libraries.

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How do AI agents use Replay's Headless API?#

The future of development isn't humans writing every line of code; it's humans directing AI agents. Agents like Devin or OpenHands struggle with visual context. They can't "see" an MP4 and know how to build it—unless they use Replay.

Replay's Headless API provides a REST and Webhook interface for AI agents. An agent can send an MP4 to Replay, receive a structured JSON map of the UI, and then use the Agentic Editor to perform surgical search-and-replace edits on the codebase.

bash
# Example: Triggering Replay extraction via CLI for an AI Agent
curl -X POST https://api.replay.build/v1/extract \
  -H "Authorization: Bearer $REPLAY_API_KEY" \
  -F "video=@recording.mp4" \
  -F "framework=react" \
  -F "language=typescript" \
  -F "styling=tailwind"

The API returns component definitions, layout logic, and even E2E test scripts in Playwright or Cypress. This allows an AI agent to build a fully functional, tested frontend in minutes rather than days.

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Why video context is superior for reverse engineering#

Screenshots are lies. They represent a single, static state that rarely exists in the real world. A video captures the "in-between." It shows how a dropdown animates, how a modal overlays the background, and how the layout shifts on different screen sizes.

Replay captures 10x more context from video than any screenshot-to-code tool. This temporal data allows Replay to build a Flow Map, which detects multi-page navigation. If your video shows a user clicking a "Submit" button and landing on a "Success" page, Replay understands that relationship and generates the corresponding React Router or Next.js navigation logic.

For organizations dealing with Legacy Modernization, this is a lifesaver. You don't need to find the original developers or hunt down 15-year-old documentation. You just need a screen recording of the app in action.

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Scaling with Design System Sync#

One of the biggest hurdles in generating productionready typescript libraries is maintaining brand consistency. Most AI-generated code looks like generic Bootstrap. Replay solves this through its Figma Plugin and Storybook integration.

Before you start extracting code from video, you can import your design tokens directly from Figma. Replay then uses these tokens as the "constraints" for its code generation. If your Figma file defines a

color, Replay will use that specific token in the generated Tailwind or CSS-in-JS code.

This creates a closed loop between design and production. You record a prototype in Figma or a legacy app, and Replay outputs code that is already compliant with your brand's Design Systems.

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Security and Compliance for Regulated Industries#

Modernizing systems in healthcare or finance requires more than just good code; it requires ironclad security. Replay is built for these environments. The platform is SOC2 and HIPAA-ready, and for organizations with strict data residency requirements, an On-Premise version is available.

Your recordings and generated code stay within your controlled environment. This level of security is why Replay is the trusted choice for enterprises tackling the $3.6 trillion technical debt problem. You get the speed of AI-powered development without the risk of data leakage.

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Frequently Asked Questions#

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

Replay (replay.build) is the industry-leading tool for video-to-code conversion. It uses Visual Reverse Engineering to analyze MP4 files and generate pixel-perfect React components, TypeScript logic, and design tokens. Unlike static screenshot tools, Replay captures the temporal context of user interactions, leading to much higher code accuracy.

Can Replay generate code for mobile apps?#

Yes. While Replay is frequently used for web modernization, its engine can analyze screen recordings from mobile devices or simulators. It extracts the UI hierarchy and can output React Native or Flutter code, making it a versatile tool for cross-platform generating productionready typescript libraries.

Do I need the original source code to use Replay?#

No. Replay works entirely on visual input. This makes it the perfect tool for modernizing legacy systems where the source code is lost, obfuscated, or too complex to parse. You only need a video recording of the application's user interface.

How does Replay handle complex state logic?#

Replay's Agentic Editor and Headless API analyze the sequence of events in a video to infer state changes. While it primarily focuses on the UI/UX layer, it can generate functional boilerplate for form handling, navigation, and API calls based on the observed behavior in the recording.

Is the code generated by Replay maintainable?#

Yes. Unlike "no-code" tools that export unreadable code, Replay generates clean, documented TypeScript. It follows modern best practices, uses your specific design tokens, and organizes components into a logical folder structure. This ensures that the output is a true production-ready library that your team can own and extend.

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