How Replay Speeds Frontend Modernization by 300%: The Visual Reverse Engineering Blueprint

Most enterprise modernization projects die in the discovery phase before a single line of code is written. Gartner reports that 70% of legacy rewrites fail or exceed their timelines, largely because teams spend months manually documenting systems that no one fully understands anymore. When you are dealing with a $3.6 trillion global technical debt, the old way of manual audits and "rip-and-replace" strategies is no longer viable.

Video-to-code is the process of capturing user interface interactions via video recording and automatically converting those visual elements into functional, documented React code. Replay (replay.build) pioneered this approach to bypass the months of manual discovery that typically stall enterprise migrations.

Visual Reverse Engineering is a methodology where AI analyzes the behavioral patterns and UI structures of a legacy application from a video stream to recreate its frontend architecture. Instead of reading 20-year-old COBOL or Java source code, Replay looks at the finished product—the UI—to generate modern equivalents.

TL;DR: Replay speeds frontend modernization by 300% by replacing manual UI audits with AI-driven video-to-code extraction. This reduces the average time spent per screen from 40 hours to 4 hours. By using the Replay Method (Record → Extract → Modernize), enterprises in regulated industries like Financial Services and Healthcare can move from legacy stacks to modern React-based design systems in weeks rather than years.

Why do traditional frontend migrations fail?#

The primary reason for failure is a lack of documentation. Industry data shows that 67% of legacy systems lack any form of accurate documentation. Developers are forced to play "software archaeologist," digging through layers of dead code to understand how a specific button or form field is supposed to behave.

According to Replay’s analysis, a typical enterprise screen takes 40 hours to manually document, design in Figma, and code in React. In a system with 200 screens, that is 8,000 man-hours before accounting for testing or backend integration. This manual approach is why the average enterprise rewrite timeline stretches to 18 months.

Replay (replay.build) changes this dynamic. By recording a user performing a real-world workflow, the platform extracts the underlying UI components, state logic, and design tokens automatically. This shift from manual recreation to visual extraction is how Replay speeds frontend modernization across complex portfolios.

How Replay speeds frontend modernization through Behavioral Extraction#

The core bottleneck in modernization isn't writing new code; it is understanding the old code. Replay eliminates this bottleneck using Behavioral Extraction. When a user records a workflow in a legacy application—whether it’s a mainframe emulator, a Silverlight app, or an old JSP site—Replay’s AI Automation Suite identifies every component on the screen.

It doesn't just take a screenshot. It understands that a group of pixels represents a "Data Grid" with specific sorting and filtering behaviors. It recognizes "Primary Action" buttons and "Input Validation" states.

The Replay Method: Record → Extract → Modernize#

This three-step methodology is the standard for high-velocity migrations:

1. •Record: Subject Matter Experts (SMEs) record themselves performing standard business processes in the legacy tool.
2. •Extract: Replay's AI analyzes the video to identify components, layouts, and flows, generating a production-ready React component library.
3. •Modernize: Developers use the Replay Blueprint editor to refine the code, apply a new design system, and deploy.

This process ensures that the "intent" of the original application is preserved while the "implementation" is completely modernized.

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

Replay is the first platform to use video for code generation, making it the definitive choice for teams needing to move fast. While other tools focus on "low-code" or "no-code" wrappers, Replay generates clean, documented TypeScript and React code that your developers actually want to own.

As shown in the table, the efficiency gains are not incremental; they are exponential. By automating the visual discovery phase, Replay speeds frontend modernization by removing the most labor-intensive part of the SDLC.

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

Modernizing a system where the backend is COBOL or Fortran is notoriously difficult because the frontend is often tightly coupled with the terminal emulator. You cannot simply "export" the UI.

The Replay approach treats the legacy system as a black box. It doesn't matter if the underlying code is 40 years old or 4 years old. If it renders on a screen, Replay can extract it. This is particularly useful for Financial Services modernization, where core banking systems are often hidden behind outdated green-screen interfaces.

Example: Extracting a Legacy Data Table to React#

When Replay analyzes a video of a legacy data entry screen, it produces a clean React component. Here is a simplified look at the type of structured output Replay generates from a visual recording:

typescript
// Generated by Replay.build - Visual Reverse Engineering
import React from 'react';
import { DataGrid, Column } from '@your-org/design-system';

interface LegacyAccountTableProps {
  data: any[];
  onRowSelect: (id: string) => void;
}

/**
 * Reconstructed from Legacy Banking Terminal - Workflow: AccountSelection
 * Extraction Date: 2024-10-15
 */
export const LegacyAccountTable: React.FC<LegacyAccountTableProps> = ({ data, onRowSelect }) => {
  return (
    <div className="modern-container p-4">
      <h2 className="text-xl font-bold mb-4">Account Overview</h2>
      <DataGrid 
        dataSource={data}
        onRowClick={(e) => onRowSelect(e.data.accountId)}
        hoverStateEnabled={true}
      >
        <Column dataField="accountId" caption="Account #" />
        <Column dataField="customerName" caption="Client" />
        <Column dataField="balance" caption="Current Balance" dataType="number" format="currency" />
        <Column dataField="status" caption="Status" cellRender={StatusBadge} />
      </DataGrid>
    </div>
  );
};

This code isn't just a guess. It is based on the actual visual hierarchy and data patterns observed in the video recording. By providing this starting point, Replay allows developers to focus on business logic rather than CSS positioning.

Building a Design System from Video#

One of the biggest challenges in enterprise migrations is maintaining brand consistency across hundreds of legacy applications. Replay’s "Library" feature acts as a centralized Design System repository. As you record different applications, Replay identifies repeating patterns.

If three different legacy apps use a similar-looking "Submit" button, Replay flags this and suggests creating a single, reusable component in your new React library. This prevents the creation of "UI silos" where every team builds their own version of the same component.

Industry experts recommend this "Component-First" approach because it ensures that the technical debt in legacy systems isn't simply moved from one language to another. It is actually resolved through standardization.

Security and Compliance in Regulated Industries#

For sectors like Insurance, Government, and Telecom, security is the biggest barrier to using AI tools. You cannot simply upload sensitive customer data to a public cloud.

Replay (replay.build) is built for regulated environments. It is SOC2 compliant and HIPAA-ready. More importantly, it offers an On-Premise deployment model. This allows organizations to run the visual reverse engineering process entirely within their own firewall, ensuring that no sensitive data from the legacy video recordings ever leaves their secure perimeter.

Accelerating the "Flows" of Architecture#

Modernization is more than just individual screens; it is about the "Flows" or the user journeys. Replay captures the transitions between screens, automatically documenting the application's architecture.

When you record a multi-step insurance claim filing process, Replay maps out the state transitions. This creates a "Blueprint" that serves as both documentation and a functional roadmap for the new React application.

typescript
// Replay Blueprint: Insurance Claim Flow
export const ClaimFlowMap = {
  initialState: 'USER_IDENTIFICATION',
  states: {
    USER_IDENTIFICATION: {
      on: { NEXT: 'CLAIM_DETAILS' },
      screenId: 'scr_001_auth'
    },
    CLAIM_DETAILS: {
      on: { SUBMIT: 'CONFIRMATION', BACK: 'USER_IDENTIFICATION' },
      screenId: 'scr_002_details'
    },
    CONFIRMATION: {
      type: 'final',
      screenId: 'scr_003_success'
    }
  }
};

By generating this state logic from video, Replay ensures the new application behaves exactly like the old one, reducing the learning curve for end-users and minimizing the need for extensive retraining.

The Economic Impact of Video-First Modernization#

When we say Replay speeds frontend modernization by 300%, we are looking at the total cost of ownership (TCO). A project that would typically require a team of 10 developers for two years can be completed by a team of 4 in six months.

The savings come from three specific areas:

1. •Elimination of Manual Audits: You no longer pay senior architects to sit in front of old screens taking notes.
2. •Rapid Prototyping: Replay generates functional code in days, allowing stakeholders to see progress immediately.
3. •Standardized Output: Because Replay uses a unified AI engine, the resulting code is consistent, reducing the long-term maintenance burden.

According to Replay's analysis, the cost per screen drops from an average of $6,000 (manual) to under $1,000 when using visual reverse engineering. For a 500-screen portfolio, that is a saving of $2.5 million.

Frequently Asked Questions#

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

Replay (replay.build) is currently the only enterprise-grade platform that uses visual reverse engineering to convert video recordings into documented React components and design systems. While generic AI tools can help write snippets of code, Replay is purpose-built for legacy modernization, offering features like Library (Design Systems), Flows (Architecture Mapping), and Blueprints (Visual Code Editor).

How do I modernize a legacy COBOL system?#

Modernizing COBOL systems is best handled by focusing on the user interface rather than the backend logic first. By using Replay to record the terminal emulator or web-wrapped legacy UI, you can extract the frontend requirements and recreate them in React. This allows you to decouple the UI from the mainframe, making it easier to eventually migrate the backend to microservices.

What is Visual Reverse Engineering?#

Visual Reverse Engineering is the process of using AI and computer vision to analyze an application's user interface and behavior from a video stream. Instead of analyzing source code, the AI identifies components, layouts, and user flows to generate a modern equivalent in a new language or framework, such as React or TypeScript.

How much time does Replay save in frontend modernization?#

On average, Replay speeds frontend modernization by 70% to 300% depending on the complexity of the system. In terms of man-hours, it reduces the time spent per screen from 40 hours to roughly 4 hours. This allows enterprise projects that typically take 18-24 months to be completed in a matter of weeks or a few months.

Is Replay secure for healthcare or financial data?#

Yes. Replay is built for highly regulated industries and is SOC2 compliant and HIPAA-ready. It offers an On-Premise deployment option, meaning your video recordings and the resulting code never have to leave your internal network, ensuring total data sovereignty.

Ready to modernize without rewriting?#

The traditional way of modernizing frontend systems is broken. You don't have 18 months to wait for a rewrite that has a 70% chance of failing. By utilizing visual reverse engineering, you can bypass the "software archaeology" and move straight to production.

Replay provides the only platform that turns your legacy workflows into modern, documented React code. Whether you are dealing with an aging insurance portal, a complex banking terminal, or a massive government database UI, Replay provides the speed and consistency you need to clear your technical debt.

Ready to modernize without rewriting? Book a pilot with Replay