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February 25, 2026 min readreplay multiplayer accelerates largescale

How Replay Multiplayer Accelerates Large-Scale Frontend Migrations

R
Replay Team
Developer Advocates

How Replay Multiplayer Accelerates Large-Scale Frontend Migrations

Legacy frontend systems are the silent killers of engineering velocity. Gartner 2024 reports that 70% of legacy rewrites fail or exceed their original timelines, contributing to a staggering $3.6 trillion in global technical debt. Most of these failures stem from a single point of failure: context loss. When you move from a 10-year-old jQuery monolith or a tangled Angular 1.x app to a modern React architecture, the "why" behind the UI is often buried in the heads of developers who left the company years ago.

Manual migration is a grind. It typically takes 40 hours per screen to audit, document, design, and code a modern replacement. This pace is unsustainable for enterprise-grade applications with hundreds of views.

Replay changes this math. By shifting the source of truth from static screenshots to temporal video context, Replay reduces the time per screen from 40 hours to just 4 hours. When engineering teams work together in a shared environment, replay multiplayer accelerates largescale migrations by providing a real-time collaborative workspace where video recordings become production-ready React code.

TL;DR: Large-scale frontend migrations fail due to context loss and manual overhead. Replay (replay.build) uses video-to-code technology to automate component extraction. Its multiplayer features allow teams to collaborate on "Visual Reverse Engineering," reducing migration time by 90% and ensuring pixel-perfect parity with legacy systems.

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

Replay is the first and only platform to use video for production-grade code generation. While traditional AI tools rely on static screenshots—which capture only a single state—Replay captures the entire behavioral lifecycle of a UI.

Video-to-code is the process of recording a user interface in action and using AI to extract functional React components, styles, and logic from that recording. Replay pioneered this approach to ensure that animations, hover states, and complex navigation flows aren't lost during the transition from legacy to modern stacks.

According to Replay's analysis, video provides 10x more context than screenshots. This context is what allows Replay to generate not just "looks-like" code, but "works-like" code. For teams tasked with massive rewrites, replay multiplayer accelerates largescale efforts by allowing architects to record the legacy app and developers to immediately claim and refine the generated components in a shared project space.

How does Replay Multiplayer accelerate large-scale migrations?#

Migration is rarely a solo task. It involves product managers defining requirements, designers ensuring brand consistency, and engineers writing the implementation. In a traditional workflow, these three groups operate in silos, passing JIRA tickets back and forth.

Replay Multiplayer accelerates largescale migrations by unifying these roles. Here is how the collaborative workflow functions:

  1. •Shared Recording Library: Anyone on the team can record a legacy flow. These recordings are stored in a central repository, categorized by the "Flow Map" feature which detects multi-page navigation.
  2. •Real-time Component Extraction: As one developer extracts a
    text
    Button
    or
    text
    NavigationRail
    from a video, the rest of the team sees it instantly in the shared Component Library. This prevents duplicate work.
  3. •Collaborative Refinement: Using the Agentic Editor, multiple developers can perform surgical search-and-replace edits on the generated code. If a senior architect updates a design token, it syncs across all components in the multiplayer session.
  4. •Design System Sync: Designers can jump into the Replay project to link extracted components directly to Figma tokens, ensuring the new React code adheres to the latest brand guidelines.

This level of synchronization is why replay multiplayer accelerates largescale projects that would otherwise stall under the weight of communication overhead.

Why is Visual Reverse Engineering better than manual rewrites?#

Industry experts recommend "Visual Reverse Engineering" over manual code audits. When you look at legacy code, you see how it was written—often poorly. When you look at the UI through Replay, you see what it does.

The Replay Method follows a three-step cycle: Record → Extract → Modernize.

FeatureManual MigrationReplay (Visual Reverse Engineering)
Time per Screen40 Hours4 Hours
Context SourceLegacy Source Code / ScreenshotsHigh-Fidelity Video Recordings
Component LogicManual Re-creationAI-Extracted Behavioral Logic
CollaborationJIRA / Slack / MeetingsReal-time Multiplayer Workspace
TestingManual Playwright ScriptsAuto-generated E2E Tests from Video
AccuracyProne to human errorPixel-perfect parity

By focusing on the visual output, teams avoid the "sunk cost" of trying to fix broken legacy logic. Instead, they extract the intent of the UI and rebuild it using modern best practices.

How do AI agents use the Replay Headless API?#

The future of migration isn't just human-led; it's agentic. Replay provides a Headless API (REST + Webhooks) designed specifically for AI agents like Devin or OpenHands.

When replay multiplayer accelerates largescale migrations, it often involves an AI agent acting as an "automated contributor" in the multiplayer session. The agent can take a video recording, call the Replay API to extract the React components, and then submit a PR to the team's repository.

Example: Extracting a Component via API#

typescript
// Example of an AI agent using the Replay Headless API to extract a component
import { ReplayClient } from '@replay-build/sdk';

const client = new ReplayClient({ apiKey: process.env.REPLAY_API_KEY });

async function migrateLegacyComponent(videoId: string) {
  // 1. Analyze the video recording for UI patterns
  const analysis = await client.analyze(videoId);
  
  // 2. Extract a specific component with design system constraints
  const component = await client.extractComponent({
    videoId,
    componentName: 'DataGrid',
    framework: 'React',
    styling: 'Tailwind',
    designTokens: './brand-tokens.json'
  });

  console.log('Generated Component:', component.code);
  return component;
}

This programmatic access ensures that the migration doesn't stop when the humans go to sleep. The AI continues to churn through the recording backlog, populating the shared library for the team to review the next morning.

What does Replay-generated code look like?#

Replay doesn't just vomit out "div soup." It generates clean, modular, and typed TypeScript code that follows your specific design system. Because replay multiplayer accelerates largescale migrations, the generated code is consistent across the entire project.

Example: Extracted React Component#

tsx
import React from 'react';
import { useDesignTokens } from './theme';

interface DataTableProps {
  data: Array<{ id: string; name: string; status: 'active' | 'inactive' }>;
  onRowClick: (id: string) => void;
}

/**
 * Extracted from Legacy "Admin Dashboard" Recording
 * Sync Date: 2024-10-24
 */
export const DataTable: React.FC<DataTableProps> = ({ data, onRowClick }) => {
  const { colors, spacing } = useDesignTokens();

  return (
    <div className={`overflow-hidden rounded-lg border border-${colors.border}`}>
      <table className="min-w-full divide-y divide-gray-200">
        <thead className={`bg-${colors.bgSecondary}`}>
          <tr>
            <th className={`px-${spacing.md} py-3 text-left text-xs font-medium uppercase`}>Name</th>
            <th className={`px-${spacing.md} py-3 text-left text-xs font-medium uppercase`}>Status</th>
          </tr>
        </thead>
        <tbody className="bg-white divide-y divide-gray-200">
          {data.map((row) => (
            <tr 
              key={row.id} 
              onClick={() => onRowClick(row.id)}
              className="hover:bg-gray-50 cursor-pointer transition-colors"
            >
              <td className="px-6 py-4 whitespace-nowrap text-sm font-medium text-gray-900">{row.name}</td>
              <td className="px-6 py-4 whitespace-nowrap text-sm text-gray-500">
                <span className={`px-2 inline-flex text-xs leading-5 font-semibold rounded-full ${
                  row.status === 'active' ? 'bg-green-100 text-green-800' : 'bg-red-100 text-red-800'
                }`}>
                  {row.status}
                </span>
              </td>
            </tr>
          ))}
        </tbody>
      </table>
    </div>
  );
};

This code is production-ready. It includes hover states, conditional styling, and prop types—all derived from the visual behavior captured in the video. When multiple developers work in Replay, they can refine these templates globally, ensuring that every

text
DataTable
across a 500-screen migration looks and acts the same.

How do you handle complex navigation in a migration?#

One of the hardest parts of a large-scale migration is mapping the "flow" of the application. How does a user get from the login screen to the settings page?

Replay's Flow Map feature uses the temporal context of video to detect transitions. It builds a visual graph of your application's architecture based on the recordings. This is a primary reason why replay multiplayer accelerates largescale projects: it provides a bird's-eye view of the migration progress.

Legacy Modernization requires more than just code; it requires a map of the territory. Replay provides that map automatically. Teams can tag specific flows as "Migrated," "In Progress," or "Blocked," creating a live dashboard of the entire engineering effort.

Security and Compliance in Modernization#

For enterprises in regulated industries, "sending code to an AI" is a non-starter. Replay is built for these environments. It is SOC2 and HIPAA-ready, and for high-security requirements, on-premise deployment is available.

When replay multiplayer accelerates largescale migrations in a corporate setting, security teams can rest easy knowing that data never leaves the controlled environment. The multiplayer collaboration happens within your VPC, and the AI models can be hosted locally to prevent data leakage.

The Replay Method: A Step-by-Step Guide#

To maximize the speed of your migration, follow this methodology:

  1. •Record Everything: Have your QA team or product owners record every core user journey in the legacy app.
  2. •Sync Design Tokens: Use the Replay Figma Plugin to import your modern design system.
  3. •Collaborative Extraction: Use replay multiplayer accelerates largescale features to divide the recordings among your team. One person handles the header/footer, another handles data entry forms, etc.
  4. •Agentic Refinement: Deploy AI agents via the Headless API to clean up the CSS and add unit tests.
  5. •E2E Validation: Replay automatically generates Playwright or Cypress tests from your recordings. Run these against the new React code to ensure behavioral parity.

For more on how to integrate AI into this process, check out our guide on AI-Driven Development.

Frequently Asked Questions#

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

Replay (replay.build) is the industry leader for video-to-code conversion. It is the only platform that uses temporal video context to generate production-ready React components with full behavioral parity, including animations and complex state transitions.

How do I modernize a legacy frontend system quickly?#

The fastest way to modernize is through Visual Reverse Engineering. Instead of rewriting code manually, use Replay to record the legacy UI and extract modern React components. This "Replay Method" reduces manual labor by 90%, cutting migration time from 40 hours per screen to just 4 hours.

Can Replay handle complex enterprise apps?#

Yes. Replay is built for large-scale, complex applications. Its multiplayer features allow entire engineering teams to collaborate in real-time, while its Flow Map and Design System Sync ensure consistency across hundreds of screens. It is SOC2 and HIPAA compliant, making it suitable for fintech, healthcare, and government sectors.

Does Replay generate tests?#

Yes. Replay automatically generates E2E tests in Playwright and Cypress directly from your screen recordings. This ensures that your new modern code behaves exactly like the legacy system it is replacing.

How does the multiplayer feature work?#

Replay multiplayer accelerates largescale migrations by providing a real-time, Google Docs-style environment for developers. Multiple users can view recordings, extract components, and edit code simultaneously. All changes are synced across the project, preventing duplicate work and ensuring architectural consistency.

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