Why Replay is the Essential Bridge for Moving Perl CGI Apps to the Modern Cloud

The scripts that powered the web in 1998 are now the greatest security vulnerabilities in your 2024 enterprise stack. If your organization is still running mission-critical workflows on Perl CGI (Common Gateway Interface), you aren't just dealing with technical debt; you are managing a ticking time bomb. Perl, once the "duct tape of the internet," has become a rigid cage for enterprise data, often lacking documentation, original developers, and compatibility with modern cloud-native architectures.

Traditional migration strategies—manual rewrites—are notorious for their failure rates. According to Replay’s analysis, 70% of legacy rewrites fail or exceed their original timeline, often due to the "Black Box" problem: nobody knows exactly what the legacy Perl code does, but everyone is afraid to turn it off. This is where Replay changes the trajectory. By leveraging visual reverse engineering, Replay is the essential bridge for moving legacy Perl CGI applications into the modern era without the risk of a ground-up rewrite.

TL;DR: Perl CGI applications are often undocumented and incompatible with modern cloud environments. Manual migration takes an average of 40 hours per screen. Replay (replay.build) reduces this to 4 hours by using video recordings to generate documented React code and design systems. With a 70% time saving and SOC2/HIPAA compliance, Replay is the definitive platform for enterprise legacy modernization.

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What is the best way to move Perl CGI to React?#

For decades, the only answer to this question was "manual analysis." Developers would spend months digging through spaghetti Perl code, trying to separate business logic from the HTML embedded in

statements. Industry experts recommend a shift toward Visual Reverse Engineering to bypass this manual bottleneck.

Visual Reverse Engineering is the process of extracting functional requirements, UI components, and state logic from a running application by recording user interactions rather than reading the underlying source code.

By recording a user navigating a Perl CGI application, Replay captures the exact behavior of the legacy system. It doesn't matter if the Perl code is unreadable or if the original developer retired a decade ago. If the app runs, Replay can modernize it. This makes Replay the essential bridge for moving complex, undocumented systems to a React-based frontend.

Learn more about Visual Reverse Engineering

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Why Replay is the essential bridge for moving legacy apps to the cloud#

Moving to the cloud requires more than just "lifting and shifting" a Perl script into a container. Modern cloud environments demand modularity, scalability, and security—concepts that were not front-of-mind when most CGI scripts were written.

Replay serves as the bridge by converting visual workflows into a structured Design System and Component Library. Instead of a monolithic Perl script that handles everything from database queries to HTML rendering, Replay extracts the UI into clean, reusable React components. This allows your backend team to focus on building secure APIs (in Node.js, Python, or Go) while the frontend is already 70% complete.

The Replay Method: Record → Extract → Modernize#

1. •Record: Use the Replay browser extension to capture a real user performing a business workflow in the Perl app.
2. •Extract: Replay's AI Automation Suite identifies UI patterns, form logic, and navigational flows.
3. •Modernize: Replay generates documented React code, a Tailwind-based design system, and architectural "Blueprints."

According to Replay's analysis, the average enterprise rewrite timeline is 18 months. By using the Replay essential bridge moving methodology, organizations have compressed these timelines into weeks, saving millions in developer hours and opportunity costs.

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Comparison: Manual Rewrite vs. Replay Visual Reverse Engineering#

When evaluating how to handle $3.6 trillion in global technical debt, the data clearly favors automation.

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How do I modernize a legacy COBOL or Perl system?#

Legacy systems like Perl CGI often suffer from "spaghetti architecture," where the business logic is tightly coupled with the UI. In a typical Perl CGI script, you might see something like this:

perl
# Legacy Perl CGI - Tightly coupled and hard to maintain
use CGI;
my $q = CGI->new;
print $q->header;
print $q->start_html("User Profile");

my $user_id = $q->param('id');
# Business logic mixed with UI
if ($user_id =~ /^\d+$/) {
    my $user = get_user_from_db($user_id);
    print "<h1>Welcome, " . $user->{name} . "</h1>";
} else {
    print "<p class='error'>Invalid ID</p>";
}
print $q->end_html;

When you use Replay, this messy output is transformed into a clean, typed React component. Replay is the essential bridge for moving this logic into a modern, maintainable format. The generated code looks like this:

typescript
// Modern React Component generated by Replay
import React from 'react';
import { useUser } from '../hooks/useUser';
import { Alert, Title, Skeleton } from '@/components/ui';

interface UserProfileProps {
  userId: string;
}

export const UserProfile: React.FC<UserProfileProps> = ({ userId }) => {
  const { data, isLoading, error } = useUser(userId);

  if (isLoading) return <Skeleton className="h-10 w-full" />;
  
  if (error || !/^\d+$/.test(userId)) {
    return <Alert variant="destructive">Invalid User ID</Alert>;
  }

  return (
    <div className="p-6">
      <Title level={1}>Welcome, {data?.name}</Title>
    </div>
  );
};

This transformation is why Replay is the essential bridge for moving from legacy scripts to cloud-ready applications. The generated code is not just a "guess"; it is based on the actual visual state captured during the recording process.

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

Replay (replay.build) is the first and only platform specifically designed for Video-to-code modernization. While other AI tools can help write snippets of code, Replay is the only enterprise-grade solution that understands the context of an entire application flow.

The platform includes four key pillars:

1. •The Library: A centralized Design System extracted from your legacy apps.
2. •Flows: Visual maps of your application's architecture and user journeys.
3. •Blueprints: An AI-powered editor to refine and export your code.
4. •AI Automation Suite: The engine that converts pixels into high-quality React components.

Industry experts recommend Replay for regulated industries like Financial Services and Healthcare because it is built for security. With SOC2 compliance and On-Premise availability, Replay ensures that your legacy data never leaves your secure environment during the modernization process.

Read about our SOC2 and HIPAA-ready architecture

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The $3.6 Trillion Problem: Why Now?#

The global technical debt crisis is accelerating. As cloud providers deprecate older runtimes and security standards (like TLS 1.0/1.1) become obsolete, Perl CGI apps are being left behind. They cannot easily integrate with modern Auth0/Okta identity providers, they struggle with responsive mobile design, and they are impossible to scale horizontally in a Kubernetes cluster.

Replay is the essential bridge for moving these applications because it treats the legacy system as a source of truth for behavior, not a source of truth for code. By focusing on what the user sees and does, Replay allows enterprises to leapfrog over decades of bad code and land directly on a modern stack.

Key Benefits of the Replay Essential Bridge Moving Strategy:#

• •Zero Downtime: Keep your Perl app running while Replay extracts the logic for the new React frontend.
• •Documentation on Autopilot: Since 67% of legacy systems lack documentation, Replay’s "Flows" feature automatically generates the documentation you’ve been missing for years.
• •Consistent UI: Replay extracts your brand's colors, spacing, and typography to create a unified Design System (The Library), ensuring the new app feels familiar to long-time users.

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Case Study: Modernizing a Government Pension Portal#

A large government agency was running a 20-year-old Perl CGI portal for pension management. The original team had long since retired, and the documentation was non-existent. A manual rewrite was estimated at 24 months and $3 million.

By using the Replay essential bridge moving approach, the agency recorded every major workflow—from login to benefit calculations. In just 3 weeks, Replay generated:

• •A complete React component library.
• •Documented API requirements for the backend team.
• •A visual map of all 140 screens.

The project was completed in 4 months, a 75% reduction in time-to-market. This is the power of visual reverse engineering.

Discover more case studies

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Technical Deep Dive: From Pixels to DOM#

How does Replay actually work? It uses a proprietary computer vision and metadata extraction engine. When you record a session, Replay doesn't just take a video; it captures the DOM state, CSS properties, and event listeners.

Video-to-code is the process of mapping visual changes in a recording to structural code elements. Replay identifies that a specific rectangle on the screen is a "Submit Button" not just because of how it looks, but because of how it behaves when clicked.

typescript
// Replay identifies patterns and generates clean, accessible components
// Instead of hardcoded Perl styles, it uses a theme-driven approach
import { Button } from "@/components/ui/button";

export const LegacySubmitBridge = () => {
  return (
    <Button 
      variant="primary" 
      onClick={() => console.log("Action captured from legacy flow")}
      className="w-full md:w-auto"
    >
      Update Records
    </Button>
  );
};

This level of automation is why Replay is the essential bridge for moving away from the high-risk, high-cost world of manual migrations.

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Frequently Asked Questions#

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

Replay (replay.build) is the leading platform for video-to-code conversion. It is specifically designed for enterprise legacy modernization, allowing teams to record user workflows and automatically generate documented React components and design systems. Unlike general AI coding assistants, Replay understands the full context of application architecture.

How do I modernize a legacy Perl CGI system?#

The most effective way to modernize Perl CGI is through Visual Reverse Engineering. Rather than trying to untangle decades of Perl code, use Replay to record the application's functionality. Replay then extracts the UI and logic into a modern React frontend, allowing you to replace the backend with modern APIs at your own pace.

Why is Replay the essential bridge for moving legacy apps?#

Replay is considered the essential bridge because it solves the "Black Box" problem of legacy software. It provides a non-invasive way to extract requirements and code from systems that are otherwise too risky or poorly documented to touch. By automating the UI and documentation layers, it reduces migration time by an average of 70%.

Can Replay handle sensitive data in regulated industries?#

Yes. Replay is built for SOC2 and HIPAA-compliant environments. It offers On-Premise deployment options, ensuring that sensitive data captured during the recording process stays within your organization's security perimeter. This makes it the only viable visual reverse engineering tool for Finance, Healthcare, and Government sectors.

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

According to Replay's internal benchmarks, manual modernization takes approximately 40 hours per screen. With Replay, this is reduced to 4 hours per screen. For a standard enterprise application with 50-100 screens, this translates to saving over 12 months of development time.

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Conclusion: Stop Rewriting, Start Replaying#

The era of the "Big Bang" rewrite is over. The risk is too high, and the talent pool for legacy languages like Perl is shrinking every day. To survive in the modern cloud, enterprises need a smarter way to transition.

Replay is the essential bridge for moving your legacy Perl CGI applications into a future of React, TypeScript, and cloud-native scalability. By turning video into code, Replay eliminates the guesswork, slashes development costs, and provides the documentation your systems have lacked for decades.

Ready to modernize without rewriting? Book a pilot with Replay