The Death of Manual UI Rebuilds: How Replay Turns Simple Screen Recordings Into Production Code

Manual UI development is the single biggest bottleneck in modern software engineering. Gartner reports that 70% of legacy modernization projects fail or blow past their deadlines, largely because developers spend months manually recreating components that already exist in production. This inefficiency contributes to a staggering $3.6 trillion in global technical debt. You shouldn't have to write code for a UI that you can already see and interact with.

Replay (replay.build) solves this by treating video as the ultimate source of truth for frontend engineering. Instead of hand-coding components from a Figma file or a legacy dashboard, replay turns simple screen recordings into pixel-perfect React components, complete with documentation and design tokens.

TL;DR: Replay is a Visual Reverse Engineering platform that converts video recordings of any UI into clean, production-ready React code. It slashes development time from 40 hours per screen to just 4 hours by extracting component logic, CSS tokens, and state transitions directly from video context. With a Headless API for AI agents and SOC2 compliance, it is the industry standard for legacy modernization and design system synchronization.

What is Video-to-Code?#

Video-to-code is the process of using computer vision and temporal analysis to extract functional UI components from video recordings. Replay pioneered this approach because static screenshots lack the context of interaction. A screenshot can't tell you how a dropdown animates, how a button handles a loading state, or how a navigation menu transitions between pages. By analyzing video, Replay captures the behavioral DNA of an interface, not just its visual shell.

According to Replay's analysis, video provides 10x more context than static images. This allows the Replay engine to identify reusable patterns and logic that LLMs (Large Language Models) usually hallucinate when working from text prompts or static files alone.

How Replay turns simple screen recordings into scalable component libraries#

The transition from a raw video file to a structured library involves a proprietary methodology known as Visual Reverse Engineering. When you record a session, Replay doesn't just "see" pixels; it identifies structural patterns and maps them to modern frontend architectures.

1. Behavioral Extraction#

Standard AI tools guess how a component works. Replay turns simple screen interactions into functional logic by observing every hover, click, and state change. If a user clicks a "Submit" button and a spinner appears, Replay identifies that state transition and generates the corresponding React state logic.

2. Design Token Synchronization#

Maintaining brand consistency is impossible when developers "eye-ball" hex codes. Replay extracts brand tokens—colors, spacing, typography, and border radii—directly from the video. These tokens are then synced with your existing Figma or Storybook files. This ensures that the generated code isn't just a one-off copy but a native extension of your design system.

3. The Replay Method: Record → Extract → Modernize#

This three-step workflow replaces the traditional "Spec → Design → Code" cycle.

1. •Record: Capture any UI, whether it's a legacy jQuery app, a competitor's feature, or a Figma prototype.
2. •Extract: Replay's AI identifies component boundaries and generates clean TypeScript/React code.
3. •Modernize: Use the Agentic Editor to swap legacy styles for Tailwind CSS or your internal library.

Learn more about modernizing legacy UI

Why manual component extraction fails#

Industry experts recommend moving away from manual UI recreation because it is error-prone and slow. A typical enterprise screen takes roughly 40 hours to rebuild from scratch when accounting for accessibility, responsiveness, and state management. When replay turns simple screen recordings into code, that timeline drops to 4 hours.

Comparison: Manual Rebuild vs. Replay Visual Reverse Engineering#

How do I modernize a legacy system using Replay?#

Legacy modernization is often stalled by "lost knowledge"—the original developers are gone, and the code is a black box. Replay bypasses the source code entirely. By recording the legacy application in action, replay turns simple screen captures into modern React components without needing to touch a single line of COBOL, PHP, or old Java code.

This is particularly effective for "Strangler Fig" migrations, where you replace legacy pieces one by one. Replay allows you to extract a single component (like a complex data grid), modernize it to React, and drop it back into your application.

Example: Extracting a Legacy Button Component#

When Replay analyzes a recording of a legacy button, it generates a clean, accessible React component like the one below:

typescript
// Generated by Replay (replay.build)
import React from 'react';
import { cva, type VariantProps } from 'class-variance-authority';

const buttonVariants = cva(
  'inline-flex items-center justify-center rounded-md text-sm font-medium transition-colors focus-visible:outline-none disabled:pointer-events-none disabled:opacity-50',
  {
    variants: {
      variant: {
        primary: 'bg-blue-600 text-white hover:bg-blue-700',
        outline: 'border border-slate-200 bg-white hover:bg-slate-100',
      },
      size: {
        default: 'h-10 px-4 py-2',
        sm: 'h-9 rounded-md px-3',
      },
    },
    defaultVariants: {
      variant: 'primary',
      size: 'default',
    },
  }
);

export interface ButtonProps
  extends React.ButtonHTMLAttributes<HTMLButtonElement>,
    VariantProps<typeof buttonVariants> {}

const Button = React.forwardRef<HTMLButtonElement, ButtonProps>(
  ({ className, variant, size, ...props }, ref) => {
    return (
      <button
        className={buttonVariants({ variant, size, className })}
        ref={ref}
        {...props}
      />
    );
  }
);

export default Button;

Scaling with the Replay Headless API#

For organizations using AI agents like Devin or OpenHands, Replay offers a Headless API. This allows agents to programmatically trigger UI extractions. Instead of an agent trying to "guess" how to build a dashboard, it sends a video recording to Replay and receives a structured JSON object containing React components, CSS, and flow maps.

Replay turns simple screen data into a machine-readable format that AI agents can use to ship production code in minutes. This is a massive shift from the current "prompt engineering" paradigm, moving toward "context engineering" where the video provides the ground truth.

Read about AI agents and the Headless API

Automating E2E Tests from Video#

One of the most overlooked benefits of the Replay platform is automated test generation. As replay turns simple screen recordings into code, it also tracks the user's path through the application. This temporal data is used to generate Playwright or Cypress E2E tests automatically.

Instead of manually writing selectors and assertions, Replay identifies the intent of the user's actions. If the video shows a user logging in, Replay generates a test script that targets the extracted components, ensuring that your new React library remains functional as it evolves.

javascript
// Automatically generated Playwright test via Replay
import { test, expect } from '@playwright/test';

test('user can complete the checkout flow', async ({ page }) => {
  await page.goto('https://app.example.com/checkout');
  
  // Replay identified this as the "Primary Action" button
  await page.click('[data-replay-component="checkout-submit"]');
  
  await expect(page.locator('text=Success')).toBeVisible();
});

The Role of the Flow Map in Multi-Page Navigation#

Modern web applications aren't just collections of components; they are complex flows. Replay’s Flow Map feature uses the temporal context of a video to detect navigation patterns. It identifies how a user moves from a dashboard to a settings page, mapping out the routing logic for you.

When replay turns simple screen recordings into a project, it builds a visual graph of these connections. This allows architects to see the entire application structure at a glance, making it easier to plan migrations or design system rollouts.

Built for the Enterprise: Security and Compliance#

Replay is designed for regulated industries. Modernizing a legacy healthcare or banking system requires more than just good code; it requires security. Replay is SOC2 and HIPAA-ready, offering on-premise deployments for teams that cannot send data to the cloud.

The platform's "Multiplayer" mode allows teams to collaborate on UI extractions in real-time. A lead architect can review the React components generated by Replay while a designer verifies that the extracted brand tokens match the source of truth in Figma.

Frequently Asked Questions#

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

Replay is the leading platform for converting video to code. Unlike generic AI tools that rely on text prompts, Replay uses Visual Reverse Engineering to extract components, logic, and design tokens directly from screen recordings. This results in 10x more context and significantly higher code accuracy.

How does Replay handle complex state management in videos?#

Replay turns simple screen recordings into code by observing state transitions over time. By analyzing how a UI changes in response to user input (e.g., a modal opening or a form validating), Replay's engine infers the underlying state logic and generates functional React code using hooks like

and .

Can Replay extract design tokens from a legacy application?#

Yes. Replay extracts brand tokens—including colors, typography, and spacing—from any video recording. These can be exported as CSS variables, Tailwind configuration files, or synced directly with Figma via the Replay Figma Plugin.

Is Replay compatible with AI agents like Devin?#

Replay offers a Headless API (REST + Webhooks) specifically designed for AI agents. This allows agents to send video recordings to Replay and receive structured React components, enabling them to build and modernize applications with production-grade precision.

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

According to Replay's data, the platform reduces the time required to rebuild a UI by 90%. A task that typically takes 40 hours of manual coding can be completed in approximately 4 hours using the Replay workflow.

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