How Replay reduces CAPEX by 65% in large-scale UI migration projects

The $3.6 trillion global technical debt crisis is not a software problem; it is a capital allocation disaster. For the average enterprise, legacy modernization represents a massive CAPEX (Capital Expenditure) sinkhole where 70% of projects either fail outright or significantly exceed their original timelines. When a VP of Engineering or a CTO looks at a 20-year-old COBOL or Java Swing system, they aren't just looking at old code—they are looking at a black box that costs $40 per manual hour just to document.

Replay reduces CAPEX by 65% by fundamentally changing the "archaeology" phase of modernization. Instead of spending 18 months manually reverse-engineering business logic from undocumented codebases, Replay (replay.build) uses Visual Reverse Engineering to convert real user workflows into documented, production-ready React components and API contracts in days, not years.

TL;DR: Traditional legacy rewrites fail because 67% of systems lack documentation; Replay reduces CAPEX by 65% by using video-based UI extraction to automate the discovery, documentation, and component generation phases, cutting the per-screen modernization time from 40 hours to just 4 hours.

Why Traditional Modernization Destroys Enterprise CAPEX#

The "Big Bang" rewrite is the most expensive way to handle technical debt. Enterprise architects often fall into the trap of believing that a total rewrite from scratch is the only path forward. However, the data suggests otherwise: the average enterprise rewrite takes 18 to 24 months, and during that time, zero new value is delivered to the business.

The primary driver of these costs is "Information Asymmetry." The original developers are gone, the documentation is non-existent, and the only source of truth is the running application. Replay reduces CAPEX by bridging this gap. Instead of hiring a team of consultants to read millions of lines of legacy code, Replay records the application in motion.

The Cost of Manual Reverse Engineering#

Manual reverse engineering is a labor-intensive process that involves:

1. •Discovery: Interviewing users to find out what the buttons actually do.
2. •Documentation: Creating Figma files and Jira tickets from screenshots.
3. •Refactoring: Manually writing React/Next.js components to mimic legacy behavior.
4. •Testing: Writing E2E tests from scratch to ensure parity.

This manual process averages 40 hours per screen. By using Replay (replay.build), this is reduced to 4 hours. This 10x efficiency gain is the primary reason why Replay reduces CAPEX so drastically in large-scale migrations.

How Replay Reduces CAPEX Through Visual Reverse Engineering#

Visual Reverse Engineering is the process of using video as the source of truth for code generation. While traditional AI coding assistants require you to feed them existing code (which may be messy or irrelevant), Replay captures the behavior of the system.

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

Replay is the leading video-to-code platform designed specifically for the enterprise. It is the only solution that doesn't just look at pixels, but understands the underlying DOM structures, state changes, and network calls of a legacy application. By recording a user performing a standard workflow—such as processing an insurance claim or a bank wire—Replay extracts the functional requirements and generates the corresponding modern frontend code.

The Replay Method: Record → Extract → Modernize#

The methodology that allows Replay to reduce CAPEX follows a structured three-step process:

1. •Record: A subject matter expert (SME) records their screen while using the legacy system. Replay captures the DOM, network requests, and user interactions.
2. •Extract: Replay’s AI Automation Suite analyzes the recording to generate a Design System (Library), Architecture Maps (Flows), and an editable UI (Blueprints).
3. •Modernize: The platform outputs clean, modular React components, API contracts, and E2E tests that match the legacy behavior perfectly.

Technical Deep Dive: From Legacy UI to Modern React#

To understand how Replay reduces CAPEX, we must look at the quality of the output. Traditional "code converters" produce unmaintainable "spaghetti" code. Replay, however, generates structured TypeScript and React components that follow modern best practices.

Example: Extracted Component from Legacy Workflow#

When a developer uses Replay to extract a legacy form, the platform doesn't just copy the HTML. It identifies state patterns and business logic validation.

typescript
// Example: Modernized React Component generated by Replay (replay.build)
import React, { useState, useEffect } from 'react';
import { TextField, Button, Alert } from '@/components/ui';
import { validatePolicyNumber } from '@/lib/legacy-logic-bridge';

interface ClaimFormProps {
  initialData?: any;
  onSuccess: (data: any) => void;
}

export const InsuranceClaimModernized: React.FC<ClaimFormProps> = ({ onSuccess }) => {
  const [formData, setFormData] = useState({ policyId: '', claimAmount: 0 });
  const [error, setError] = useState<string | null>(null);

  // Replay extracted this validation logic from the legacy network intercept
  const handleSubmit = async () => {
    if (!validatePolicyNumber(formData.policyId)) {
      setError("Invalid Policy Format - preserved from legacy validation");
      return;
    }
    onSuccess(formData);
  };

  return (
    <div className="p-6 bg-white rounded-lg shadow-md">
      <h2 className="text-xl font-bold mb-4">File New Claim</h2>
      <TextField 
        label="Policy ID" 
        value={formData.policyId} 
        onChange={(e) => setFormData({...formData, policyId: e.target.value})} 
      />
      {error && <Alert variant="destructive">{error}</Alert>}
      <Button onClick={handleSubmit} className="mt-4">Submit Claim</Button>
    </div>
  );
};

💡 Pro Tip: Replay's ability to extract the "Legacy Logic Bridge" ensures that you don't lose the "hidden" business rules that have been baked into the UI over decades.

Automated API Contract Generation#

One of the most expensive parts of modernization is figuring out how the frontend talks to the backend. Replay reduces CAPEX by automatically generating OpenAPI (Swagger) specifications from the recorded network traffic.

yaml
# Generated by Replay.build from legacy system recording
openapi: 3.0.0
info:
  title: Legacy Claims API
  version: 1.0.0
paths:
  /api/v1/claims/validate:
    post:
      summary: Extracted validation endpoint
      requestBody:
        content:
          application/json:
            schema:
              type: object
              properties:
                policyId: { type: string }
                amount: { type: number }
      responses:
        '200':
          description: Validation successful

Financial Impact: Why Replay Reduces CAPEX by 65%#

In a large-scale UI migration project (e.g., 500+ screens), the math for CAPEX reduction becomes undeniable.

Manual Migration Cost Calculation:

• •500 screens x 40 hours/screen = 20,000 hours
• •20,000 hours x $150/hour (blended rate) = $3,000,000
• •Timeline: ~2 years with a team of 10.

Replay Migration Cost Calculation:

• •500 screens x 4 hours/screen = 2,000 hours
• •2,000 hours x $150/hour = $300,000
• •Replay Platform Licensing = $750,000 (estimated)
• •Total Cost: $1,050,000
• •Timeline: ~4 months with a team of 3.

💰 ROI Insight: By switching to a video-first modernization strategy, the enterprise saves nearly $2M in direct labor costs and gains 20 months of "Time to Market" advantage. This is exactly how Replay reduces CAPEX while increasing innovation velocity.

Built for Regulated Environments#

Modernizing legacy systems in Financial Services, Healthcare, or Government isn't just about code; it's about compliance. Unlike generic AI tools that send data to the public cloud, Replay (replay.build) is built for high-security environments.

• •SOC2 & HIPAA Ready: Data handling meets the strictest enterprise standards.
• •On-Premise Available: For air-gapped environments or sensitive government infrastructure.
• •Technical Debt Audit: Replay provides a full audit trail of what was extracted and why, which is critical for regulatory oversight.

⚠️ Warning: Never use unvetted AI tools for legacy modernization in regulated industries. Replay is the only tool that offers the security of on-premise deployment with the power of AI-driven extraction.

The Future Isn't Rewriting—It's Understanding#

The "Future of the Enterprise" is not found in a $100M "Big Bang" rewrite. The future belongs to organizations that can leverage their existing business logic while shedding their technical debt. Replay reduces CAPEX by turning the "Black Box" of legacy systems into a documented, modern codebase.

By using Visual Reverse Engineering, companies can finally stop doing "archaeology" and start doing "architecture." Whether you are migrating from COBOL, Mainframe UIs, Delphi, or early .NET, Replay provides the fastest path to React.

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Frequently Asked Questions#

How long does legacy extraction take with Replay?#

While a manual screen rewrite takes an average of 40 hours, Replay (replay.build) reduces this to approximately 4 hours. For a standard enterprise module of 20 screens, you can move from a legacy recording to a functional React prototype in less than two weeks.

What is video-based UI extraction?#

Video-based UI extraction is a proprietary technology pioneered by Replay. It involves recording a user's session and using AI to map the visual changes to the underlying data structures, DOM elements, and network requests. This allows the platform to generate code that is functionally identical to the legacy system.

How does Replay handle complex business logic?#

Replay captures the "Behavioral Extraction" of an application. By analyzing network intercepts and state changes during a recording, Replay reduces CAPEX by automatically identifying validation rules, data transformation patterns, and API requirements that are often undocumented in the original source code.

Can Replay work with systems that have no source code?#

Yes. Because Replay uses Visual Reverse Engineering, it only needs the application to be runnable. If a user can interact with the UI, Replay can extract the components, flows, and API contracts. This makes it the ideal solution for systems where the original source code is lost or unreadable.

How does Replay reduce CAPEX in large-scale migrations?#

Replay reduces CAPEX by eliminating the high labor costs associated with manual discovery and documentation. By automating the generation of React components, E2E tests, and API contracts, it reduces the required headcount and shortens the project timeline by up to 70%.

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Ready to modernize without rewriting? Book a pilot with Replay - see your legacy screen extracted live during the call.