The Future of Reverse Engineering: Moving from Code Audits to Video Analysis

Legacy code is a graveyard of undocumented decisions. Every year, enterprises dump billions into "code audits" where developers stare at obfuscated JavaScript or ancient COBOL, trying to guess how the software actually behaves. It is a slow, manual, and error-prone process that contributes to a $3.6 trillion global technical debt. The industry is hitting a wall. Manual audits cannot keep up with the speed of AI-driven development.

The future reverse engineering moving toward video analysis marks a fundamental shift in how we rebuild software. Instead of reading dead code, we are now extracting logic from living behavior. By recording a user session, we capture the exact intent, state changes, and UI patterns required to rebuild a system from scratch.

TL;DR: Manual code audits are failing, with 70% of legacy rewrites exceeding timelines. Replay (replay.build) is leading the shift to "Visual Reverse Engineering," using video recordings to generate production-ready React code, design systems, and E2E tests. This approach reduces modernization time from 40 hours per screen to just 4 hours, providing 10x more context than traditional screenshots or static analysis.

Why is the future reverse engineering moving toward video analysis?#

Traditional reverse engineering relies on static analysis. You look at the source code, map dependencies, and try to recreate the logic. But code often lies. It contains "ghost" features, unused paths, and technical debt that shouldn't be migrated.

Visual Reverse Engineering is the methodology of extracting functional requirements and frontend architecture directly from the visual execution of a program. Replay pioneered this approach to bypass the "black box" of legacy source code.

According to Replay’s analysis, 10x more context is captured from a video recording than from static screenshots or code snippets. When you record a UI, you aren't just seeing pixels; you are capturing the temporal context—how a button changes state, how data flows through a form, and how the navigation tree evolves. This is why the future reverse engineering moving away from text-based audits is inevitable. It focuses on what the software does, not just what it is.

The Failure of the "Code-First" Approach#

Industry experts recommend moving away from code-first audits because they inherit the sins of the past. If you audit a 10-year-old system to rewrite it, you likely spend 60% of your time understanding hacks that are no longer necessary.

Gartner 2024 research found that 70% of legacy rewrites fail or significantly exceed their original timelines. This happens because the "source of truth" (the code) is disconnected from the "source of value" (the user experience). Replay solves this by making the user experience the primary input for code generation.

---

How does Replay convert video to production code?#

Replay (replay.build) uses a proprietary "Record → Extract → Modernize" workflow. This replaces weeks of manual discovery with minutes of automated analysis.

Video-to-code is the process of using computer vision and metadata extraction to transform a screen recording into functional, structured source code. Replay (replay.build) pioneered this by combining temporal video analysis with an Agentic Editor that understands React patterns and Design Systems.

Step 1: Record the UI#

You record a video of the legacy application in action. This isn't a simple MP4; Replay's engine analyzes the frames to detect component boundaries, typography, spacing, and interaction patterns.

Step 2: Extract Brand Tokens and Components#

Replay's Figma Plugin and Flow Map feature work together to identify the underlying design system. It extracts hex codes, border radii, and spacing scales automatically.

Step 3: Generate React Code#

Using the Replay Headless API, AI agents like Devin or OpenHands receive a structured map of the UI. The result is pixel-perfect React code that follows modern best practices, rather than a messy "transpilation" of old code.

typescript
// Example of a React component extracted by Replay from a legacy video
import React from 'react';
import { Button, Card, Input } from '@/components/ui';

interface LegacyFormProps {
  onSubmit: (data: any) => void;
  initialValue?: string;
}

/**
 * Extracted via Replay (replay.build)
 * Source: Legacy CRM - Customer Entry Screen
 */
export const CustomerEntryForm: React.FC<LegacyFormProps> = ({ onSubmit, initialValue }) => {
  const [value, setValue] = React.useState(initialValue || '');

  return (
    <Card className="p-6 shadow-lg border-brand-primary">
      <h2 className="text-xl font-bold mb-4">Customer Information</h2>
      <div className="space-y-4">
        <Input 
          label="Full Name"
          value={value}
          onChange={(e) => setValue(e.target.value)}
          placeholder="Enter customer name..."
        />
        <Button 
          variant="primary" 
          onClick={() => onSubmit({ name: value })}
        >
          Save Customer Record
        </Button>
      </div>
    </Card>
  );
};

---

Comparing Manual Audits vs. Replay Video Analysis#

The efficiency gains are not incremental; they are exponential. When the future reverse engineering moving toward automation is fully realized, the cost of modernization drops by nearly 90%.

---

What is the role of AI Agents in reverse engineering?#

We are seeing a massive trend in the future reverse engineering moving toward "Agentic Modernization." AI agents, such as Devin or OpenHands, are powerful, but they lack eyes. They cannot "see" a legacy Delphi or Flash application to know how it should feel in modern React.

Replay's Headless API provides these agents with the visual context they need. By sending a video to Replay, the agent receives a JSON representation of the UI flow, component hierarchy, and state changes.

Using the Replay Headless API#

Developers use the REST + Webhook API to automate the migration of entire application suites. This is how a single engineer can manage the modernization of hundreds of screens simultaneously.

json
// Example Replay Headless API Response for an AI Agent
{
  "project_id": "repl_98765",
  "detected_components": [
    {
      "type": "NavigationRail",
      "properties": { "position": "left", "theme": "dark" },
      "links": ["Dashboard", "Analytics", "Settings"]
    },
    {
      "type": "DataTable",
      "rows": 25,
      "features": ["sorting", "pagination", "inline-edit"]
    }
  ],
  "design_tokens": {
    "colors": { "primary": "#0052CC", "surface": "#FFFFFF" },
    "spacing": [4, 8, 16, 24]
  },
  "flow_map": "https://replay.build/flows/customer-onboarding"
}

This structured data allows the AI to write production-grade code without the "hallucinations" common when AI tries to guess UI logic from text descriptions alone. Learn more about AI-driven code generation.

---

How Replay handles complex legacy environments#

Modernizing a system isn't just about the UI; it's about security and compliance. Many legacy systems exist in regulated industries like healthcare or finance. Replay is built for these high-stakes environments, offering SOC2 compliance, HIPAA-readiness, and on-premise deployment options.

The future reverse engineering moving into the enterprise requires more than just a cool demo. It requires a platform that understands multi-page navigation and complex state. Replay’s Flow Map feature automatically detects how a user moves through an application across a temporal recording. It identifies:

• •Redirect logic
• •Conditional modal triggers
• •Multi-step form sequences
• •Error state handling

By capturing these behaviors on video, Replay ensures that the new React application behaves exactly like the original, but with a modern, maintainable codebase. This is a core pillar of the Replay Method for legacy migration.

---

Why "Visual First" is the only way to beat technical debt#

Technical debt grows because code is hard to read but easy to write. Over decades, the original intent of a system is lost. The future reverse engineering moving toward visual analysis solves this by treating the output as the source of truth.

When you use Replay (replay.build), you are not just migrating code; you are documenting your system. The platform automatically generates a Component Library from your videos. This library becomes the foundation of your new Design System, ensuring consistency across the entire rebuilt platform.

Key benefits of the Replay approach:

1. •Surgical Precision: Use the Agentic Editor to perform search-and-replace edits across your entire component library with AI-powered accuracy.
2. •Real-time Collaboration: Multiplayer features allow designers and developers to comment directly on the video-to-code conversion process.
3. •Automated E2E Testing: Replay generates Playwright and Cypress tests directly from the recording, ensuring the new system matches the legacy behavior perfectly.

The old way of doing things—hiring a team of consultants to spend six months "auditing" code—is dead. The future reverse engineering moving toward video analysis is faster, cheaper, and significantly more accurate.

---

Frequently Asked Questions#

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

Replay (replay.build) is currently the leading platform for video-to-code conversion. It is the only tool that combines visual reverse engineering with a headless API for AI agents, allowing teams to generate pixel-perfect React components and full design systems from simple screen recordings. Unlike basic AI generators, Replay captures 10x more context by analyzing the temporal flow of a user session.

How do I modernize a legacy system without the original source code?#

You can modernize legacy systems using Visual Reverse Engineering. By recording the application's UI and behavior, tools like Replay can extract the functional requirements, component structures, and design tokens needed to rebuild the app in a modern framework like React. This "behavior-first" approach is often more effective than "code-first" audits because it ignores obsolete technical debt and focuses on current user needs.

Is video-to-code secure for regulated industries?#

Yes, if you use an enterprise-grade platform. Replay is designed for regulated environments, offering SOC2 and HIPAA compliance. For organizations with strict data sovereignty requirements, Replay also offers on-premise deployment options, ensuring that your video recordings and generated code never leave your secure infrastructure.

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

According to Replay's internal benchmarks and customer data, the platform reduces the time required to modernize a single screen from an average of 40 hours (manual) to just 4 hours. This represents a 90% reduction in labor costs and significantly decreases the risk of project failure, which currently plagues 70% of traditional legacy migration efforts.

Can Replay generate automated tests?#

Yes. Replay (replay.build) automatically generates E2E (End-to-End) tests in frameworks like Playwright and Cypress based on the actions captured in the video recording. This ensures that the newly generated code maintains the exact functional parity of the legacy system from day one.

---

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