Legacy Modernization Case Studies: 5 Global Enterprises Who Cut Costs by 50%

Most enterprise modernization projects are dead before the first line of code is written. The industry standard for a full-scale digital transformation is an 18-month timeline, yet 70% of legacy rewrites fail or exceed their original timeline. We are currently looking at a $3.6 trillion global technical debt crisis where organizations are spending 80% of their IT budget just to "keep the lights on" for systems that no longer serve their business goals.

The bottleneck isn't a lack of talent; it’s a lack of visibility. 67% of legacy systems lack documentation, forcing architects to perform "archaeological coding"—digging through thousands of lines of undocumented COBOL or jQuery to understand a single business rule. This is why the industry is shifting toward Visual Reverse Engineering.

TL;DR: Legacy modernization fails because of poor documentation and manual rebuilding costs. By using Replay, global enterprises in finance, healthcare, and manufacturing are reducing modernization costs by 50% and cutting timelines from 18 months to weeks. This article explores five legacy modernization case studies where visual reverse engineering replaced manual rewrites, saving millions in technical debt.

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The Hidden Cost of Manual Modernization#

According to Replay’s analysis, the average manual rewrite of a single enterprise screen takes 40 hours. This includes discovery, UI design, state management planning, and frontend development. For an enterprise application with 200 screens, that’s 8,000 developer hours—or roughly $1.2 million in labor alone—before you even touch the backend.

Industry experts recommend moving away from the "Big Bang" rewrite. Instead, the focus has shifted to automated extraction. This is where video-to-code technology changes the ROI equation.

Video-to-code is the process of converting screen recordings of legacy user interfaces into production-ready, documented React components and design systems using machine learning and visual analysis.

By using Replay, teams reduce that 40-hour-per-screen metric down to just 4 hours. Below, we examine five legacy modernization case studies that prove this 10x efficiency gain is the new standard for the enterprise.

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1. Global Financial Services: From Mainframe UI to React in 6 Weeks#

A Tier-1 investment bank faced a critical issue: their core trading terminal was built on a legacy framework that only ran in Internet Explorer. With IE’s end-of-life, they faced a compliance nightmare. Their initial estimate for a manual rewrite was 24 months and a $5 million budget.

The primary challenge was the "Black Box" effect. The original developers had retired, and the business logic was buried in the UI's state handling.

The Implementation#

Instead of reading the source code, the bank used Replay to record 150 critical workflows. Replay’s AI Automation Suite analyzed the visual patterns and extracted a consistent Design System.

The Result:

• •Manual Estimate: 24 Months
• •Actual Timeline: 6 Weeks
• •Cost Savings: 62% reduction in developer overhead.

Technical Output: Standardizing the Component Library#

The bank was able to generate a standardized TypeScript component library that mirrored the legacy functionality but utilized modern CSS-in-JS patterns.

typescript
// Generated by Replay Visual Reverse Engineering
import React from 'react';
import styled from 'styled-components';

interface TradeDataGridProps {
  data: Array<{ id: string; ticker: string; price: number; volume: number }>;
  onTradeSelect: (id: string) => void;
}

const GridContainer = styled.div`
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1px;
  background-color: var(--enterprise-border-color);
  border: 1px solid var(--enterprise-border-color);
`;

export const TradeDataGrid: React.FC<TradeDataGridProps> = ({ data, onTradeSelect }) => {
  return (
    <GridContainer role="grid">
      {data.map((row) => (
        <React.Fragment key={row.id}>
          <div onClick={() => onTradeSelect(row.id)}>{row.ticker}</div>
          <div>{row.price.toLocaleString('en-US', { style: 'currency', currency: 'USD' })}</div>
          <div>{row.volume}</div>
          <button onClick={() => onTradeSelect(row.id)}>Execute</button>
        </React.Fragment>
      ))}
    </GridContainer>
  );
};

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2. Healthcare Provider: Modernizing EHR Systems for HIPAA Compliance#

In the healthcare sector, modernization isn't just about aesthetics; it's about patient safety and data integrity. A regional healthcare provider was struggling with an Electronic Health Record (EHR) system that was 15 years old.

The complexity of healthcare workflows makes these legacy modernization case studies particularly difficult. A single "Patient Intake" flow might involve 12 different modal windows and 50+ input fields.

The Replay Advantage#

The provider used Replay to map "Flows." By recording real clinicians using the system, they generated visual blueprints of every edge case. This eliminated the "Discovery Phase," which typically accounts for 30% of project costs.

According to Replay’s analysis, healthcare organizations using visual reverse engineering see a 70% faster path to SOC2 and HIPAA-ready UI deployments because the generated code follows a strict, pre-defined security architecture.

Learn more about modernizing regulated systems

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3. Insurance Giant: Consolidating 40 Years of Technical Debt#

Insurance companies often grow through acquisitions, leading to a fragmented ecosystem of "Frankenstein" applications. One global insurer had 14 different claims processing portals, all with different UI patterns but identical business logic.

Legacy Modernization Case Studies: The Comparison Table#

The insurer conducted a head-to-head trial: one team used traditional manual refactoring, while the other used Replay’s Library feature to create a unified Design System.

The insurer successfully unified all 14 portals into a single React-based platform, cutting maintenance costs by $2.4M annually.

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4. Manufacturing ERP: Moving Heavy Data Grids to the Cloud#

Manufacturing ERPs are notorious for "Heavy Grids"—interfaces that display thousands of rows of inventory data with complex filtering logic. These systems are often built in Silverlight or Delphi, making them nearly impossible to port to modern web standards manually.

The Technical Challenge#

Mapping complex state transitions in a data-heavy environment is where most legacy modernization case studies fail. Developers often struggle to replicate the exact "feel" of legacy keyboard shortcuts and cell editing.

Replay’s "Blueprints" editor allowed the manufacturing firm's architects to see the exact state transitions of the legacy grid and export them as React hooks.

typescript
// Example of extracted state logic for a complex ERP Grid
import { useState, useCallback } from 'react';

export const useInventoryState = (initialData: any[]) => {
  const [gridData, setGridData] = useState(initialData);
  const [filters, setFilters] = useState({});

  const handleCellEdit = useCallback((rowId: string, columnId: string, newValue: any) => {
    setGridData(prev => prev.map(row => 
      row.id === rowId ? { ...row, [columnId]: newValue } : row
    ));
    // Replay automatically identified this as a critical sync point for the legacy API
    console.log(`Syncing ${columnId} for row ${rowId} to backend...`);
  }, []);

  return { gridData, handleCellEdit, setFilters };
};

By automating the UI extraction, the manufacturing firm shifted their senior engineers' focus to the high-value task: migrating the underlying SQL databases to a modern microservices architecture on AWS.

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5. Government Agency: Accessibility and Security at Scale#

Government systems are often the oldest in existence. One federal agency was operating a system where the "documentation" was a 400-page PDF from 2004. They needed to meet modern WCAG 2.1 accessibility standards—a task that is notoriously difficult when refactoring legacy code.

Using Replay, the agency recorded the legacy workflows. Replay’s AI Automation Suite didn't just copy the code; it upgraded it. It identified non-accessible elements in the legacy UI and generated React components with proper ARIA labels and semantic HTML.

Key Statistic: The agency reduced their technical debt by 55% in the first year by decommissioning legacy servers and moving to a serverless React frontend.

Explore our guide on UI Automation

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Why Visual Reverse Engineering is the Future#

Traditional modernization is a "bottom-up" approach. You look at the code, try to understand it, and then try to build a UI that matches. This is fundamentally flawed because the code is often a mess of patches and workarounds.

Replay enables a "top-down" approach. By starting with the user's reality—the UI they interact with every day—you capture the intent of the system.

Benefits of the Replay Approach:#

1. •Zero Documentation Required: Replay creates the documentation by analyzing the recordings.
2. •Visual Parity: Users don't need retraining because the new system looks and feels like the one they know, just faster and more reliable.
3. •Clean Codebase: Instead of "spaghetti React" that mimics legacy logic, Replay generates clean, modular components based on modern best practices.

Industry experts recommend that enterprises stop treating modernization as a coding problem and start treating it as a translation problem. When you translate via visual patterns, you bypass the complexity of the legacy source code.

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Technical Implementation: The Replay Workflow#

To achieve the results seen in these legacy modernization case studies, teams follow a streamlined four-step process:

1. •Record: Use the Replay recorder to capture standard business workflows.
2. •Analyze: Replay’s AI identifies components (buttons, inputs, tables, navbars) and creates a Design System.
3. •Map: Use "Flows" to connect screens and define the application architecture.
4. •Export: Download production-ready React code, complete with TypeScript definitions and documentation.

This workflow is what allows a team of three developers to do the work of a thirty-person department.

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Frequently Asked Questions#

How do legacy modernization case studies justify the cost of new tools?#

Most enterprises justify the cost by comparing the "Cost of Inaction" (maintenance of technical debt) against the "Cost of Modernization." When using tools like Replay, the ROI is usually achieved within the first 3 months because the 90% reduction in discovery time pays for the platform immediately.

Can Replay handle complex business logic hidden in the UI?#

Yes. By recording multiple variations of a workflow, Replay’s AI can infer conditional logic and state transitions. While the most complex backend calculations still require API integration, the frontend state management—which accounts for the majority of UI bugs—is captured with high fidelity.

Is Visual Reverse Engineering secure for regulated industries?#

Platforms like Replay are built for high-security environments. With SOC2 compliance, HIPAA-readiness, and On-Premise deployment options, organizations in Finance and Healthcare can modernize their stacks without their data ever leaving their controlled environment.

What happens to the old backend during this process?#

Most organizations use a "Strangler Fig" pattern. They use Replay to build the modern frontend and then slowly replace legacy backend APIs one by one. This allows for a continuous delivery model rather than a risky "Big Bang" release.

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Conclusion#

The data from these legacy modernization case studies is clear: the manual way of rewriting software is obsolete. With a 70% failure rate and a $3.6 trillion debt looming over the industry, the move toward automated, visual-first modernization is inevitable.

By cutting costs by 50% and shrinking timelines from years to weeks, Replay is helping the world's largest organizations reclaim their agility.

Ready to modernize without rewriting? Book a pilot with Replay