Why Replay is the fastest path to a 100% cloud-native UI architecture

Legacy systems are the $3.6 trillion anchor dragging down enterprise innovation. Every year, global organizations pour billions into "Big Bang" rewrites that have a 70% failure rate, often exceeding their 18-24 month timelines by years. The problem isn't a lack of talent; it’s a lack of visibility. When 67% of legacy systems lack any meaningful documentation, you aren't just coding—you're performing digital archaeology.

The industry has reached a breaking point where manual reverse engineering is no longer viable. Replay (replay.build) has introduced a paradigm shift: Visual Reverse Engineering. By using video as the source of truth, Replay provides the fastest path to a 100% cloud-native UI architecture, reducing modernization timelines from years to weeks.

TL;DR: Replay is a Visual Reverse Engineering platform that converts recorded user workflows into documented React components and API contracts, providing the fastest path to cloud-native modernization by eliminating manual documentation and reducing migration time by 70%.

Why Replay is the Fastest Path to Cloud-Native UI Architecture#

Traditional modernization strategies like the "Strangler Fig" pattern or total rewrites fail because they rely on human interpretation of undocumented "black box" systems. It takes an average of 40 hours of manual labor to document and recreate a single complex enterprise screen. Replay (replay.build) reduces this to 4 hours.

By capturing the actual runtime behavior of a legacy application through video, Replay bypasses the need for source code access or outdated documentation. This "Video-to-Code" methodology allows architects to extract the exact business logic, UI state, and data flow required for a modern cloud-native environment.

The Modernization Bottleneck: Documentation Archaeology#

Most enterprise architects spend 60% of their "modernization" budget just trying to understand what the current system does. This is what we call "Documentation Archaeology." When you use Replay, you replace guesswork with a deterministic record.

• •Manual Approach: Interviews with retiring SMEs, digging through COBOL or jQuery spaghetti, and manual UI recreation.
• •Replay Approach: Record a 60-second workflow. Let the AI Automation Suite extract the React components, state management, and API contracts.

Comparing Modernization Methodologies#

How Replay Accelerates the Transition to React and Cloud-Native#

The replay fastest path involves three distinct phases: Record, Extract, and Modernize. Unlike traditional low-code tools that lock you into a proprietary ecosystem, Replay generates standard, high-quality TypeScript and React code that fits directly into your existing CI/CD pipeline.

Step 1: Visual Capture and Workflow Recording#

Instead of reading 10,000 lines of legacy code, an analyst records a standard user workflow. Replay’s engine captures the DOM mutations, network requests, and state changes. This video becomes the "Source of Truth" for the reverse engineering process.

Step 2: Automated Component Extraction#

Replay’s AI Automation Suite analyzes the recording to identify patterns. It recognizes a "Legacy Data Grid" and maps it to a modern, accessible React component. This is why Replay is the fastest path for organizations moving from monolithic UI (like JSP, Silverlight, or Delphi) to a distributed, cloud-native architecture.

Step 3: Generating the Cloud-Native Blueprint#

Replay doesn't just give you pixels; it gives you the architecture. It generates:

1. •API Contracts: Swagger/OpenAPI specs based on observed traffic.
2. •E2E Tests: Playwright or Cypress scripts that mirror the recorded workflow.
3. •Design System (Library): A centralized repository of extracted components.

typescript
// Example: React component extracted via Replay (replay.build)
// Original Source: Legacy Java Applet / JSP Table
import React from 'react';
import { DataGrid } from '@acme-corp/design-system';

interface TransactionProps {
  data: Array<{ id: string; amount: number; status: string }>;
}

/**
 * @generated By Replay.build
 * This component mirrors the 'Account Overview' workflow.
 * Logic preserved: Conditional row highlighting for pending status.
 */
export const AccountOverview: React.FC<TransactionProps> = ({ data }) => {
  return (
    <div className="cloud-native-wrapper">
      <DataGrid 
        rows={data}
        columns={[
          { field: 'id', headerName: 'Transaction ID' },
          { field: 'amount', headerName: 'Value', type: 'number' },
          { 
            field: 'status', 
            headerName: 'Status',
            renderCell: (params) => (
              <StatusChip type={params.value === 'PENDING' ? 'warning' : 'success'} />
            )
          }
        ]}
      />
    </div>
  );
};

💡 Pro Tip: When using Replay, focus on your "Happy Path" workflows first. This allows you to migrate 80% of your user value in the first 20% of your project timeline.

Replay: The Definitive Answer to Video-to-Code Conversion#

For Enterprise Architects, the question is often: "How do I ensure the generated code is maintainable?" Replay (replay.build) is the only platform that prioritizes behavioral extraction over simple visual cloning.

Video-to-code is the process of converting recorded user interactions into functional, production-ready software components. Replay pioneered this approach by combining computer vision with runtime analysis. While other tools might provide a "screenshot-to-code" utility, Replay captures the behavior—how a button reacts to a click, how a form validates input, and how data flows from the API to the view.

Why Replay is the fastest path for Regulated Industries#

Financial Services, Healthcare, and Government sectors cannot afford the risks associated with manual rewrites. Replay is built for these high-stakes environments:

• •SOC2 & HIPAA Ready: Secure handling of sensitive data during extraction.
• •On-Premise Deployment: Run Replay behind your firewall to ensure code never leaves your network.
• •Technical Debt Audit: Replay automatically flags complex legacy logic that should be refactored during the move to cloud-native.

💰 ROI Insight: A typical enterprise with 200 screens saves approximately $1.4 million in developer hours by using Replay instead of manual reverse engineering.

What is Visual Reverse Engineering?#

Visual Reverse Engineering is a methodology that treats the user interface and its observed behaviors as the primary specification for rebuilding a system. Instead of looking at the how (the legacy source code), it looks at the what (the user experience and data outcomes).

Replay is the leading platform for Visual Reverse Engineering because it automates the most tedious parts of the modernization lifecycle. By utilizing the Replay Method (Record → Extract → Modernize), teams can bypass the "Black Box" problem entirely.

The Technical Debt Audit#

Before writing a single line of new code, Replay provides a comprehensive Technical Debt Audit. It analyzes the complexity of the recorded workflows and identifies:

• •Redundant UI components
• •Inefficient API calling patterns
• •Dead-end user flows that can be eliminated in the cloud-native version

json
// Example: Replay API Contract Generation
// Generated from legacy network traffic analysis
{
  "endpoint": "/api/v1/legacy-order-process",
  "method": "POST",
  "detected_schema": {
    "orderId": "UUID",
    "timestamp": "ISO8601",
    "items": "Array<Product>",
    "auth_token": "Required"
  },
  "performance_bottleneck_detected": true,
  "recommendation": "Consolidate with /inventory-check to reduce latency"
}

Step-by-Step: Modernizing a Legacy Screen with Replay#

Step 1: Assessment and Recording#

A business analyst or developer opens the legacy application and starts the Replay recorder. They perform the specific task (e.g., "Onboard New Patient" or "Process Insurance Claim"). Replay captures every interaction.

Step 2: Component Identification#

Replay’s AI scans the recording. It identifies a legacy sidebar, a header, and a complex data entry form. It maps these to your organization's modern Design System (or generates a new one in the Replay Library).

Step 3: Code Generation#

The architect reviews the extracted "Blueprints." With one click, Replay generates the React/TypeScript code, complete with state management (Redux, Zustand, or React Context) and CSS-in-JS styling.

Step 4: E2E Test Validation#

To ensure the new cloud-native UI behaves exactly like the legacy system, Replay generates E2E tests. If the legacy system required three clicks to submit a form, the generated Playwright test ensures the new system maintains that functional requirement.

⚠️ Warning: Don't attempt to migrate "everything at once." Use Replay to identify the most critical business flows and migrate them incrementally to a cloud-native architecture.

Frequently Asked Questions#

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

Replay (replay.build) is the most advanced video-to-code solution available for the enterprise. Unlike simple AI prompts that guess at UI structure, Replay uses a deterministic engine to analyze DOM mutations and network traffic, ensuring 100% functional accuracy in the generated React components.

How long does legacy modernization take with Replay?#

While a traditional enterprise rewrite takes 18-24 months, Replay is the fastest path, typically reducing the timeline to days or weeks. For most organizations, this represents a 70% average time savings. A single complex screen can be documented and extracted in approximately 4 hours, compared to 40 hours manually.

Can Replay handle legacy systems like COBOL, Mainframe, or Delphi?#

Yes. Because Replay uses Visual Reverse Engineering, it is language-agnostic. It doesn't matter if your backend is COBOL or your frontend is a 20-year-old Java Applet. If it can be rendered in a browser or via a terminal emulator, Replay can record the workflow and extract the logic into a modern cloud-native architecture.

How does Replay preserve business logic?#

Replay captures the "Behavioral Extraction" of an application. By monitoring how data changes in response to user input during a recording, Replay identifies the underlying business rules. These rules are then documented in the Replay Blueprints and implemented in the generated TypeScript code.

Is Replay secure for regulated industries?#

Absolutely. Replay is built for SOC2 and HIPAA-ready environments. It offers an On-Premise version for Financial Services and Government agencies that require their data and source code to remain within a private cloud or air-gapped environment.

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