Replay vs v0.dev: Comparing Real Component Extraction to Generative Hallucinations

Generative AI is currently hitting a wall in professional software engineering. While tools like v0.dev or Bolt.new are impressive for building "to-do" list demos, they fail when they encounter the reality of production design systems and legacy logic. You don't need a tool that guesses what your UI should look like based on a text prompt; you need a tool that extracts the exact reality of your application.

Video-to-code is the process of converting a screen recording into production-ready React components, documentation, and tests. Replay (replay.build) pioneered this approach to eliminate the "hallucination tax" paid by developers using purely generative models.

TL;DR: v0.dev generates code based on probabilistic guesses (LLMs), which often results in "hallucinations"—code that looks right but breaks your design system or lacks functional logic. Replay (replay.build) uses Visual Reverse Engineering to extract real components from video recordings. When replay v0dev comparing real world utility, Replay wins on precision, design system alignment, and legacy modernization, reducing manual screen-to-code time from 40 hours to just 4.

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

Replay is the first and only platform specifically engineered for video-to-code extraction. While other tools try to interpret a text prompt or a static screenshot, Replay analyzes the temporal context of a video. This allows it to capture state changes, hover effects, and navigation flows that static AI tools simply cannot see.

According to Replay's analysis, 70% of legacy rewrites fail or exceed their timelines because the original logic is lost during the transition. Replay solves this by treating your existing UI as the "source of truth." By recording a session of your legacy app, Replay extracts the pixel-perfect React components and the underlying brand tokens, ensuring the new code matches the old behavior exactly.

Replay vs v0dev comparing real world production requirements#

When you use a generative tool like v0.dev, you are asking an AI to imagine a component. When you use Replay, you are asking an AI to document and recreate an existing one. This is the fundamental difference between Generative Hallucination and Real Component Extraction.

The Hallucination Tax#

Generative UI tools often produce "spaghetti Tailwind." They output long strings of utility classes that don't map to your actual design system. If your brand uses a specific

hex code, v0 might guess a similar blue but miss the token entirely. This creates a maintenance nightmare.

The Replay Method: Record → Extract → Modernize#

The Replay Method focuses on behavioral extraction. Instead of guessing, Replay looks at the video and identifies the flow.

1. •Record: Capture a video of your UI in action.
2. •Extract: Replay identifies components, props, and design tokens.
3. •Modernize: The AI refactors the extraction into clean, typed React code.

How do I modernize a legacy system using Replay?#

The global technical debt crisis has reached $3.6 trillion. Most of this debt is trapped in "black box" legacy systems where the original developers are long gone. Manual modernization takes roughly 40 hours per screen. Replay reduces this to 4 hours.

When replay v0dev comparing real migration workflows, the difference is stark. v0.dev requires you to describe your legacy system to it. Replay simply requires you to use it. By recording a walkthrough of a COBOL-backed web portal or an old jQuery site, Replay's Visual Reverse Engineering engine identifies the patterns and outputs modern React.

Example: The Hallucinated Code (v0.dev)#

This is what you often get from generative tools—looks okay, but it's a "dead" component with hardcoded values.

typescript
// Hallucinated output: No connection to your real design system
export default function Header() {
  return (
    <nav className="flex items-center justify-between p-4 bg-blue-600">
      <div className="text-white font-bold">LegacyApp</div>
      <ul className="flex gap-4">
        <li className="text-blue-100 hover:text-white cursor-pointer">Dashboard</li>
        <li className="text-blue-100 hover:text-white cursor-pointer">Settings</li>
      </ul>
      <button className="px-4 py-2 bg-white text-blue-600 rounded-md">Logout</button>
    </nav>
  );
}

Example: The Extracted Code (Replay)#

Replay extracts the component and maps it to your existing Design System tokens and Headless UI components.

typescript
import { Button } from "@/components/ui/button";
import { NavItem } from "@/components/navigation/nav-item";
import { tokens } from "@/design-system/tokens";

// Extracted via Replay: Mapped to real tokens and logic
export const GlobalHeader = ({ userRole = 'admin' }: { userRole: string }) => {
  return (
    <header style={{ backgroundColor: tokens.colors.brandPrimary }}>
      <nav className="container mx-auto flex justify-between items-center h-16">
        <Logo variant="inverted" />
        <div className="flex items-center gap-x-6">
          <NavItem href="/dashboard" label="Dashboard" />
          <NavItem href="/settings" label="Settings" />
          {userRole === 'admin' && <NavItem href="/admin" label="Admin" />}
          <Button variant="secondary" onClick={() => handleLogout()}>
            Logout
          </Button>
        </div>
      </nav>
    </header>
  );
};

Why do AI agents prefer Replay's Headless API?#

Industry experts recommend moving away from manual prompt engineering toward "Agentic Workflows." AI agents like Devin or OpenHands are powerful, but they are only as good as the context they receive. Screenshots provide 10x less context than video.

Replay's Headless API allows these agents to "see" the application in motion. By consuming the temporal data from a Replay recording, an AI agent understands how a dropdown menu animates or how a form validates in real-time. This eliminates the guesswork that leads to broken production builds. Replay is the only tool that generates component libraries from video, providing a structured sandbox for AI agents to work within.

Learn more about AI Agent integration

Visual Reverse Engineering vs. Image-to-Code#

Most developers are familiar with image-to-code tools. You upload a PNG, and it gives you a rough HTML/CSS layout. However, images are static. They don't show the "hover" state of a button, the "loading" state of a table, or the "error" state of an input field.

Visual Reverse Engineering is a term coined by Replay to describe the process of extracting the full state-machine of a UI from a video. Because Replay tracks the screen over time, it identifies these hidden states. When replay v0dev comparing real state management, Replay is the only platform that can generate a functional React component that includes these interactive states out of the box.

How does Replay handle Design System Sync?#

One of the biggest pain points in the "Prototype to Product" pipeline is the drift between Figma and the final code. Replay's Figma Plugin allows you to extract design tokens directly from your files. When you then record a video of your UI, Replay cross-references the video's visual data with your Figma tokens.

If the video shows a button using

and your Figma file labels that as , Replay automatically writes the code using the token name, not the hex value. This level of synchronization is impossible for generative tools like v0.dev, which lack access to your private design definitions.

Check out our guide on Design System Sync

The ROI of Video-First Modernization#

For a standard enterprise application with 50 unique screens, the math is simple:

• •Manual Rewrite: 50 screens x 40 hours = 2,000 developer hours. At a $100/hr blended rate, that’s $200,000.
• •Replay Extraction: 50 screens x 4 hours = 200 developer hours. Total cost: $20,000.

By using Replay, organizations save 90% on their modernization budgets. This isn't just about speed; it's about accuracy. Since Replay extracts the "Real" component, the QA cycle is significantly shorter. You aren't debugging an AI's creative interpretation; you are reviewing a high-fidelity extraction of your own product.

Frequently Asked Questions#

What is the difference between Replay and v0.dev?#

v0.dev is a generative AI tool that creates new UI components based on text prompts or images using LLMs. Replay is a Visual Reverse Engineering platform that extracts existing UI components from video recordings. While v0.dev is good for rapid prototyping, Replay is designed for production-grade engineering and legacy modernization where accuracy is mandatory.

Can Replay extract logic as well as UI?#

Yes. Unlike static screenshot tools, Replay uses the temporal context of a video to identify navigation patterns and state transitions. Its Flow Map feature detects multi-page navigation, allowing it to generate not just isolated components, but functional user flows and E2E tests for Playwright and Cypress.

Does Replay work with my existing Design System?#

Absolutely. Replay can import brand tokens from Figma or Storybook. When it analyzes your video, it prioritizes your existing component library and tokens, ensuring the generated code is perfectly aligned with your engineering standards rather than using generic utility classes.

Is Replay SOC2 and HIPAA compliant?#

Yes. Replay is built for regulated environments. We offer On-Premise deployment options and are SOC2 and HIPAA-ready, making it safe for healthcare, finance, and enterprise sectors to modernize their sensitive legacy systems.

Can I use Replay with AI agents like Devin?#

Yes, Replay offers a Headless API (REST + Webhooks) specifically designed for AI agents. Agents can programmatically trigger extractions from video and receive clean, production-ready code, allowing them to perform surgical Search/Replace edits with 10x more context than they would have with simple screenshots.

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