The Cost of "Keeping the Lights On": An Analysis of Enterprise IT Budgets

Enterprise IT budgets are currently cannibalized by a silent killer: the "Legacy Tax." While most CTOs believe they are investing in innovation, the reality is that 70% to 80% of the average enterprise IT budget is spent simply "keeping the lights on" (KLO). This isn't just a maintenance fee; it is the price of complexity, technical debt, and the sheer impossibility of understanding systems built two decades ago.

TL;DR: The cost of maintaining legacy systems consumes up to 80% of IT budgets; Replay slashes this burden by using visual reverse engineering to automate documentation and component extraction, reducing modernization timelines from years to weeks.

The Mathematical Impossibility of the "Big Bang" Rewrite#

The global technical debt has ballooned to $3.6 trillion. For a Fortune 500 company, this manifests as a "Black Box" problem: core business logic resides in systems where the original authors have long since retired, and the documentation is either non-existent or dangerously outdated.

When leadership realizes that KLO costs are stifling growth, the instinct is often a "Big Bang" rewrite. This is statistically the most dangerous path an Enterprise Architect can recommend.

• •70% of legacy rewrites fail or significantly exceed their original timelines.
• •18 to 24 months is the average duration for an enterprise-scale rewrite.
• •67% of legacy systems lack any form of reliable documentation.

The result? You spend $10M+ to end up exactly where you started, but with a new set of bugs and a team that is burnt out from two years of "software archaeology."

Comparing Modernization Strategies#

The Archaeology Problem: Why Manual Extraction Fails#

In a traditional modernization project, the first three to six months are spent in "discovery." This involves senior engineers—your most expensive assets—diving into ancient COBOL, Java 6, or legacy .NET codebases to map out what the system actually does versus what the business thinks it does.

This manual "archaeology" costs an average of 40 hours per screen. If your enterprise application has 200 screens, you are looking at 8,000 hours of discovery before a single line of modern code is written.

⚠️ Warning: Manual discovery is the leading cause of "Scope Creep." Without a visual source of truth, developers often miss edge cases in business logic that only appear in specific user workflows.

Replay changes this dynamic by shifting the source of truth from the obfuscated code to the user workflow. By recording real user interactions, Replay performs visual reverse engineering to generate documented React components and API contracts automatically. This reduces the time per screen from 40 hours to 4 hours.

From Video to Documented Codebase: The Replay Workflow#

Modernization shouldn't require a time machine. Replay allows you to record a legacy workflow and instantly generate the underlying architecture. This isn't just a "screen grab"; it is a deep-packet inspection of the UI, state, and network layers.

Step 1: Workflow Recording#

Instead of reading 10,000 lines of legacy JavaScript, a business analyst or QA lead records the actual process (e.g., "Onboarding a New Insurance Policy"). Replay captures every DOM change, network request, and state transition.

Step 2: Visual Extraction#

Replay’s AI Automation Suite analyzes the recording. It identifies reusable UI patterns and maps them to your modern Design System.

Step 3: Code Generation#

Replay generates clean, typed React components that mirror the legacy behavior but utilize modern best practices.

typescript
// Example: Replay-generated component from a legacy Financial Services portal
// Logic preserved from legacy workflow, rendered in modern React/Tailwind

import React, { useState, useEffect } from 'react';
import { Button, Input, Alert } from '@/components/ui'; // From your Replay Library
import { validatePolicySchema } from './legacy-logic-bridge';

interface PolicyFormProps {
  initialData?: any;
  onTransition: (nextStep: string) => void;
}

export const PolicyOnboarding: React.FC<PolicyOnboardingProps> = ({ initialData, onTransition }) => {
  const [formData, setFormData] = useState(initialData);
  const [error, setError] = useState<string | null>(null);

  // Replay extracted this validation logic from the legacy XHR intercept
  const handleNextStep = async () => {
    const isValid = await validatePolicySchema(formData);
    if (isValid) {
      onTransition('UNDERWRITING_REVIEW');
    } else {
      setError('Invalid Policy Parameters: Check Legacy Field 402B');
    }
  };

  return (
    <div className="p-6 border rounded-lg bg-white shadow-sm">
      <h2 className="text-xl font-bold mb-4">Policy Submission</h2>
      <div className="space-y-4">
        <Input 
          label="Policy Holder Name"
          value={formData.holderName}
          onChange={(e) => setFormData({...formData, holderName: e.target.value})}
        />
        {/* Replay identified this as a critical legacy business rule component */}
        <RiskAssessmentModule data={formData.riskScore} /> 
        
        {error && <Alert variant="destructive">{error}</Alert>}
        
        <Button onClick={handleNextStep} className="w-full">
          Continue to Underwriting
        </Button>
      </div>
    </div>
  );
};

💡 Pro Tip: Use Replay's "Flows" feature to generate E2E tests (Playwright/Cypress) automatically from your recordings. This ensures that your modernized version has 100% parity with legacy behavior.

The Cost of "Black Box" API Contracts#

The most significant hidden cost in enterprise IT is the integration layer. Legacy systems often communicate via undocumented, proprietary APIs. When you try to modernize the frontend, the backend becomes a bottleneck because no one knows the required payload structures.

Replay automatically generates API Contracts by observing the network traffic during the recording phase.

yaml
# Generated by Replay AI Automation Suite
# Legacy Endpoint: /api/v1/internal/proc/legacy_submit
openapi: 3.0.0
info:
  title: Legacy Policy Submission API
  version: 1.0.4
paths:
  /legacy_submit:
    post:
      summary: Extracted from "New Policy" Workflow
      requestBody:
        content:
          application/json:
            schema:
              type: object
              properties:
                uuid: { type: string, format: uuid }
                policy_type: { type: integer, description: "Map: 1=Life, 2=Auto" }
                legacy_flags: { type: string, pattern: "^[A-Z0-2]{4}$" }

💰 ROI Insight: Automating API contract generation saves an average of 15 hours per endpoint by eliminating the need for manual packet sniffing and backend code review.

Implementing Visual Reverse Engineering: A 3-Step Guide#

For Enterprise Architects, the goal is to move from "Discovery" to "Delivery" as fast as possible. Here is how to implement Replay in a regulated environment (Healthcare, FinServ, Gov).

Step 1: The Technical Debt Audit#

Run a Replay audit on your top 10 highest-maintenance screens. Replay will generate a technical debt score based on component complexity, CSS nesting depth, and the number of undocumented API calls.

Step 2: Building the Library#

Use Replay’s Library feature to identify UI patterns across your legacy estate. Instead of building 50 different buttons, Replay identifies that 50 legacy screens use the same underlying pattern and maps them to a single modern React component.

Step 3: Blueprint Generation#

Export your recordings into Replay Blueprints. These are the "Instruction Manuals" for your developers. A Blueprint includes:

• •The visual recording of the workflow.
• •The extracted React code.
• •The API requirements.
• •The E2E test suite.

Security and Compliance in Regulated Industries#

We understand that "Cloud-only" is often a non-starter for Financial Services or Government sectors. The cost of a security breach far outweighs the cost of legacy maintenance.

• •SOC2 & HIPAA Ready: Replay is built with enterprise-grade security.
• •On-Premise Availability: Run Replay entirely within your own VPC or air-gapped environment.
• •PII Redaction: Replay automatically masks sensitive user data during the recording and extraction process, ensuring that no customer data ever enters the modernization pipeline.

📝 Note: Replay does not require access to your source code repository. It works by observing the output of the application, making it ideal for systems where the source code is lost or too fragile to touch.

Frequently Asked Questions#

How long does legacy extraction take with Replay?#

While a manual rewrite of a complex module takes 18-24 months, Replay users typically see fully documented and extracted components in 2 to 8 weeks. The "Discovery" phase is reduced from months to days.

What about business logic preservation?#

Replay captures the behavioral truth. By recording the inputs and outputs of every user action, we create a functional map of the business logic. Our AI Automation Suite then translates these behaviors into modern TypeScript logic, ensuring parity with the legacy system.

Can Replay handle mainframe or terminal-based systems?#

Yes. If the system has a web-based wrapper or can be accessed via a browser-based emulator, Replay can record the workflow and extract the underlying data structures and UI patterns.

Does this replace my developers?#

No. Replay replaces the boring, manual archaeology that developers hate. It frees your senior architects to focus on system design and innovation rather than digging through 20-year-old spaghetti code.

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