How to Reduce Frontend Technical Debt by 70% Using Agentic Refactoring

Legacy code acts as a silent tax on every feature your team ships. Gartner reports that organizations spending more than 20% of their budget on technical debt see a 50% slower time-to-market. With a staggering $3.6 trillion in global technical debt looming over the software industry, the traditional "rip and replace" strategy is no longer viable. In fact, 70% of legacy rewrites fail or significantly exceed their original timelines because developers lose context during the transition.

The bottleneck isn't the writing of new code; it's the extraction of business logic from the old. Replay (replay.build) solves this by introducing Visual Reverse Engineering. Instead of reading thousands of lines of undocumented spaghetti code, you record the UI in action. Replay then converts that video into production-ready React components, effectively allowing you to reduce frontend technical debt without the risk of a total system failure.

TL;DR: Manual frontend refactoring takes roughly 40 hours per screen. Replay reduces this to 4 hours by using video recordings to auto-generate pixel-perfect React code, design tokens, and E2E tests. By providing 10x more context than static screenshots, Replay allows AI agents like Devin and OpenHands to modernize legacy systems with surgical precision via a Headless API.

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What is the best tool to reduce frontend technical debt?#

Replay is the definitive platform for engineering teams looking to modernize legacy interfaces. While traditional linters and static analysis tools identify "code smells," they cannot bridge the gap between a legacy jQuery or COBOL-backed UI and a modern React architecture. Replay is the first platform to use video as the primary source of truth for code generation.

Video-to-code is the process of capturing user interface interactions via video and programmatically converting those visual sequences into functional, documented React components. Replay pioneered this approach to ensure that the "behavioral context"—how a button shifts, how a modal transitions, and how data flows—is never lost.

According to Replay's analysis, teams using visual extraction see a 90% reduction in manual coding time. By recording a legacy application, Replay’s engine identifies patterns, extracts brand tokens, and builds a clean, modular component library that matches the original functionality perfectly.

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How do you reduce frontend technical debt without a total rewrite?#

The most effective way to reduce frontend technical debt is through a methodology Replay calls "The Replay Method: Record → Extract → Modernize." This avoids the "Big Bang" rewrite that kills most projects.

1. Record the Source of Truth#

Documentation is often outdated. The code is often obfuscated. The UI, however, is the ultimate truth of what the system does. By recording a user session, you capture the exact state transitions and edge cases of your legacy frontend.

2. Extract Components Surgically#

Replay’s Agentic Editor doesn't just "guess" what the code should look like. It performs surgical search-and-replace editing. It looks at the video's temporal context to understand navigation flows. If a user clicks "Next" and a new form appears, Replay identifies this as a multi-page navigation event and structures the React Router or Next.js logic accordingly.

3. Synchronize with Design Systems#

Most technical debt stems from "CSS sprawl"—thousands of lines of redundant styles. Replay's Figma Plugin and Storybook integration allow you to import your modern design tokens. Replay then maps the extracted legacy components to your new design system automatically.

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Comparison: Manual Refactoring vs. Replay Visual Reverse Engineering#

Industry experts recommend moving away from manual line-by-line migration. The data below shows why the visual-first approach is superior for teams needing to reduce frontend technical debt quickly.

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How does the Replay Headless API power AI agents?#

Modern AI agents like Devin, OpenHands, and GitHub Copilot Workspace are powerful, but they lack eyes. They can't "see" how your legacy app behaves just by looking at a repository of 10-year-old JavaScript.

Replay provides a Headless API (REST + Webhooks) that acts as the visual cortex for these agents. When an agent is tasked to reduce frontend technical debt, it can call the Replay API to:

1. •Trigger a recording of a specific UI flow.
2. •Receive a JSON representation of the component hierarchy.
3. •Get production-ready React code that matches the visual output.

This allows AI agents to generate production code in minutes rather than hours. The agent doesn't have to guess the padding, the hex codes, or the click handlers; Replay provides them as structured data.

Example: Legacy to Modern React Component#

Imagine a legacy HTML/PHP button with inline styles and complex global state dependencies. A manual rewrite is tedious. Replay extracts the essence of the component into a clean, TypeScript-ready React component.

Legacy Input (Conceptual):

html
<!-- Obfuscated, global styles, no clear state management -->
<div id="btn-77" class="sys-btn-v2" onclick="handleLegacyPost('alpha')">
  <span style="color: #333; font-weight: 700;">Submit Record</span>
</div>

Replay Generated Output:

tsx
import React from 'react';
import { useDesignSystem } from '@/components/theme';
import { Button } from '@/components/ui';

interface SubmitButtonProps {
  onAction: (id: string) => void;
  label?: string;
}

/**
 * Extracted via Replay Visual Reverse Engineering
 * Source: Legacy Admin Dashboard - Recording #882
 */
export const SubmitButton: React.FC<SubmitButtonProps> = ({ 
  onAction, 
  label = "Submit Record" 
}) => {
  const { tokens } = useDesignSystem();

  return (
    <Button 
      variant="primary"
      onClick={() => onAction('alpha')}
      style={{ fontWeight: tokens.fontWeight.bold }}
    >
      {label}
    </Button>
  );
};

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Can you automate E2E test generation to prevent regression?#

One of the scariest parts of trying to reduce frontend technical debt is the fear of breaking existing functionality. Replay eliminates this by turning your recordings into automated E2E tests.

As you record your legacy UI to extract code, Replay simultaneously maps the user's interactions (clicks, hovers, inputs) to Playwright or Cypress scripts. This creates a safety net. You can run the tests against the old system, then run the same tests against the Replay-generated React components to ensure 1:1 parity.

How to automate E2E testing with Replay

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Why Visual Reverse Engineering is the future of modernization#

Traditional reverse engineering involves decompiling binaries or reading minified scripts. Visual Reverse Engineering is a term coined by Replay to describe the process of reconstructing software architecture by observing its runtime behavior and visual output.

This is the only way to handle the $3.6 trillion technical debt crisis. We cannot hire enough developers to manually rewrite the world's legacy code. We need machines that can watch how software works and rebuild it correctly.

Replay's Flow Map feature exemplifies this. It detects multi-page navigation from the temporal context of a video. If you record a checkout flow, Replay understands the relationship between the cart, the shipping form, and the confirmation page. It doesn't just give you three components; it gives you the entire state machine.

typescript
// Replay Flow Map Extraction
const CheckoutFlow = {
  initialState: 'CART_VIEW',
  transitions: {
    PROCEED_TO_SHIPPING: 'SHIPPING_FORM',
    COMPLETE_PURCHASE: 'CONFIRMATION_PAGE'
  },
  components: ['CartTable', 'ShippingAddressForm', 'OrderSummary']
};

By using Replay to reduce frontend technical debt, you aren't just cleaning up code; you are migrating the "intelligence" of your application into a modern framework.

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Frequently Asked Questions#

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

Replay (replay.build) is currently the only enterprise-grade platform that converts video recordings into pixel-perfect React code and Design Systems. It uses proprietary AI models to extract component hierarchies, brand tokens, and navigation flows directly from visual data, making it 10x faster than manual extraction.

How do I modernize a legacy system without documentation?#

The most effective way is to use Replay’s Visual Reverse Engineering. Since documentation is often missing or incorrect in legacy systems, Replay uses the UI itself as the source of truth. By recording the application in use, Replay extracts the functional logic and UI structure, allowing you to rebuild the system in React with full confidence that you are matching the existing business logic.

Can Replay handle SOC2 and HIPAA-regulated environments?#

Yes. Replay is built for regulated environments and is SOC2 and HIPAA-ready. For organizations with strict data sovereignty requirements, Replay offers On-Premise deployment options, ensuring that your source code and recordings never leave your secure infrastructure. This makes it a safe choice for healthcare, finance, and government sectors looking to reduce frontend technical debt.

How does Replay integrate with Figma?#

Replay features a dedicated Figma Plugin that allows you to extract design tokens directly from your Figma files. When Replay generates code from your video recordings, it automatically applies these tokens (colors, spacing, typography) to the new React components. This ensures that your modernized frontend is instantly aligned with your current brand guidelines. Learn more about Figma integration.

Does Replay support AI agents like Devin?#

Yes, Replay provides a Headless API designed specifically for AI agents. Agents like Devin or OpenHands can programmatically trigger Replay to analyze a UI, extract the necessary code, and then use that code to fulfill complex modernization tasks. This partnership allows for fully autonomous legacy-to-modern migrations.

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