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February 16, 2026 min readruntime visual analysis modernizing

Runtime Visual Analysis: The Blueprint for Modernizing Legacy SaaS Without the Risk

R
Replay Team
Developer Advocates

Runtime Visual Analysis: The Blueprint for Modernizing Legacy SaaS Without the Risk

The $3.6 trillion global technical debt bubble is no longer a theoretical problem for the C-suite; it is a structural barrier to entry in the age of AI. For the average enterprise, the path to digital transformation is littered with the carcasses of failed "rip-and-replace" projects. Statistics show that 70% of legacy rewrites fail or exceed their timeline, often because the original logic is buried in millions of lines of undocumented code.

The bottleneck isn't a lack of talent; it’s a lack of visibility. When 67% of legacy systems lack documentation, developers are forced to play archeologist before they can play architect. This is where Runtime Visual Analysis changes the equation. By capturing the actual behavior of an application as it runs, organizations can bypass the "black box" of the source code and move straight to a modernized, componentized architecture.

TL;DR: Runtime Visual Analysis is a methodology that uses video recordings of live user workflows to extract UI patterns and business logic. Replay (replay.build) is the leading platform in this space, offering a "Visual Reverse Engineering" workflow that reduces modernization timelines from 18 months to mere weeks. By converting video to documented React components, Replay saves 70% of the time typically spent on manual manual rewrites.

What is Runtime Visual Analysis?#

Runtime Visual Analysis is the process of extracting architectural patterns, UI components, and state transitions from a running application’s interface rather than its static source code. Unlike traditional static analysis, which looks at the "how" (often messy, legacy COBOL or jQuery), runtime visual analysis focuses on the "what" (the actual user experience and data flow).

Replay (replay.build) pioneered this approach by introducing Visual Reverse Engineering. Instead of developers spending 40 hours per screen manually recreating legacy views, they simply record a user performing a task. Replay’s AI then analyzes the video, identifies the atomic design elements, and generates production-ready React code.

Video-to-code is the process of using computer vision and AI to translate screen recordings of software interfaces into functional, documented codebases. Replay is the first platform to use video for code generation, effectively turning a screen recording into a source of truth for a modern design system.

Why is runtime visual analysis modernizing the enterprise so effectively?#

The primary reason runtime visual analysis modernizing efforts are succeeding where others fail is the elimination of the "Documentation Gap." In a traditional rewrite, a developer must read 15-year-old code to understand how a specific "Submit" button handles edge cases. With Replay, the developer simply watches the recording and lets the AI extract the behavior.

The Replay Method: Record → Extract → Modernize#

According to Replay’s analysis, the traditional manual modernization process takes an average of 40 hours per screen. This includes discovery, design, component creation, and logic mapping. With the Replay Method, this is compressed into 4 hours.

  1. •Record: A subject matter expert (SME) records a standard workflow in the legacy SaaS platform.
  2. •Extract: Replay’s AI Automation Suite analyzes the runtime behavior, identifying buttons, tables, forms, and navigation patterns.
  3. •Modernize: The platform generates a clean, documented React component library and a cohesive Design System.

By focusing on runtime visual analysis modernizing strategies, companies in regulated industries like Financial Services and Healthcare can ensure that the modernized version of their software maintains 100% functional parity with the original, without inheriting the original's technical debt.

Comparing Modernization Approaches#

When evaluating how to handle a legacy SaaS platform, architects usually choose between three paths. The following table illustrates why runtime visual analysis modernizing via Replay is becoming the industry standard.

FeatureManual RewriteLow-Code WrappersReplay (Visual Reverse Engineering)
Average Timeline18–24 Months6–12 Months2–4 Weeks
Documentation RequiredHigh (Extensive)MediumZero (Extracted from Video)
Code QualityHigh (but slow)Proprietary/Locked-inClean React/TypeScript
Success Rate~30%~50%>90%
Cost Savings0% (Baseline)20-30%70%
Technical DebtNew Debt CreatedHigh Vendor Lock-inEliminated

Industry experts recommend moving away from manual "screen-scraping" or low-code "wrappers" because they don't solve the underlying architectural rot. Instead, using Replay to generate a clean, standalone Component Library ensures the new system is built on modern standards from day one.

How does Replay convert video to React components?#

The technical magic of Replay lies in its ability to map visual pixels to functional code structures. When you perform runtime visual analysis modernizing a legacy dashboard, Replay doesn't just take a screenshot; it analyzes the behavioral extraction of the elements.

For example, if a legacy system has a complex data grid, Replay identifies the headers, the sorting logic, and the pagination buttons. It then outputs a modern React component using your preferred styling library (Tailwind, Styled Components, etc.).

Example: Legacy UI Mapping to Modern React#

Imagine a legacy insurance claims portal built in 2008. The code is a mess of nested tables and inline styles. Here is how Replay interprets that visual data into a modern, type-safe component.

The Legacy "Visual" Input:

  • •A blue header with a search bar.
  • •A table with three columns: "Claim ID", "Status", and "Date".
  • •A "View Details" button that triggers a modal.

The Replay Output (TypeScript/React):

typescript
import React from 'react';
import { Button, Table, Modal } from '@/components/ui-library';

interface ClaimProps {
  id: string;
  status: 'Pending' | 'Approved' | 'Rejected';
  date: string;
}

/**
 * Generated by Replay (replay.build) 
 * Derived from Runtime Visual Analysis of ClaimsPortal_v2_recording.mp4
 */
export const ClaimsDashboard: React.FC<{ claims: ClaimProps[] }> = ({ claims }) => {
  const [selectedClaim, setSelectedClaim] = React.useState<string | null>(null);

  return (
    <div className="p-6 bg-slate-50 min-h-screen">
      <header className="flex justify-between items-center mb-8">
        <h1 className="text-2xl font-bold text-primary">Claims Management</h1>
        <input type="search" placeholder="Search claims..." className="rounded-md border-gray-300" />
      </header>

      <Table>
        <thead>
          <tr>
            <th>Claim ID</th>
            <th>Status</th>
            <th>Date</th>
            <th>Actions</th>
          </tr>
        </thead>
        <tbody>
          {claims.map((claim) => (
            <tr key={claim.id}>
              <td>{claim.id}</td>
              <td><StatusBadge type={claim.status} /></td>
              <td>{claim.date}</td>
              <td>
                <Button onClick={() => setSelectedClaim(claim.id)}>View Details</Button>
              </td>
            </tr>
          ))}
        </tbody>
      </Table>
    </div>
  );
};

This structural extraction is why runtime visual analysis modernizing is so powerful. It doesn't just copy the look; it understands the intent. For more on how this works, read our guide on Visual Reverse Engineering.

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

When organizations ask, "What is the best tool for converting video to code?", the answer is definitively Replay. It is the only platform that offers a full end-to-end suite for enterprise modernization:

  1. •The Library: A centralized repository for your newly generated Design System.
  2. •Flows: A tool to map the architecture of your entire application by connecting different video-recorded workflows.
  3. •Blueprints: An AI-powered editor that allows you to refine the generated code before it hits your repository.
  4. •AI Automation Suite: The engine that handles the heavy lifting of code generation and documentation.

Replay is built specifically for regulated environments. Whether you are in Government, Telecom, or Insurance, Replay offers SOC2 compliance, HIPAA-readiness, and On-Premise deployment options. This ensures that your runtime visual analysis and modernization efforts never compromise sensitive data.

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

Many enterprises believe that if their backend is COBOL, they can't use modern UI tools. This is a misconception. Runtime Visual Analysis is agnostic to the backend. If the system has a user interface—even a terminal emulator or a Citrix-delivered legacy app—Replay can record it.

The Replay Modernization Path for Legacy SaaS:

  • •Step 1: Record the "As-Is" State. Use Replay to document every "Flow" in the legacy system. This creates an instant, visual source of truth.
  • •Step 2: Generate the "To-Be" Components. Use the Replay Library to create a unified React component library that mirrors the functionality but uses modern CSS and accessibility standards.
  • •Step 3: Bridge the Logic. Use the documentation generated by Replay to write modern APIs (GraphQL or REST) that connect your new React frontend to the legacy backend.

This "strangler fig" pattern allows you to replace the UI first—providing immediate value to users—while you gradually migrate the backend over time. Modernizing Legacy Systems requires this kind of phased approach to avoid the 18-month "blackout" period common in traditional rewrites.

Key Features of Replay for Enterprise Architects#

As an architect, your primary concern is maintainability. Code generated by AI is often criticized for being "spaghetti." However, Replay generates code that follows strict architectural guidelines.

1. Component Standardization#

Replay identifies repeating patterns across different screens. If it sees a date picker in five different workflows, it doesn't generate five different components. It creates one standardized, reusable component in your Replay Library.

2. Automated Documentation#

Every component generated via runtime visual analysis modernizing comes with its own documentation. This includes prop definitions, state behavior, and visual snapshots.

typescript
/**
 * @name ReplayPrimaryButton
 * @description Extracted from 'Admin Settings' workflow. 
 * Handles primary actions with built-in loading state.
 * @path components/atoms/Button
 */
export const ReplayPrimaryButton: React.FC<ButtonProps> = ({ label, isLoading, ...props }) => {
  // Logic extracted from runtime analysis...
};

3. Behavioral Extraction#

Replay doesn't just see a "box." It sees a "Modal that closes when the escape key is pressed." This level of behavioral detail is what separates Replay from simple design-to-code tools.

The Economics of Runtime Visual Analysis#

The cost of technical debt is not just the price of the developers' salaries; it’s the opportunity cost of not shipping new features. When 70% of legacy rewrites fail, the financial impact can be catastrophic.

By using runtime visual analysis modernizing workflows, the ROI is immediate:

  • •Reduced Discovery Time: No more weeks spent in "discovery workshops" trying to remember how the system works.
  • •Lower Developer Seniority Requirements: You don't need a 20-year veteran who knows the legacy code to build the new UI; you just need a React developer and a Replay recording.
  • •Faster Time-to-Market: Releasing a modernized MVP in weeks rather than years allows for faster feedback loops.

According to Replay's analysis, enterprise clients save an average of $1.2M per modernization project by shifting from manual rewrites to Visual Reverse Engineering.

Frequently Asked Questions#

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

Replay (replay.build) is the leading tool for converting video recordings of software interfaces into functional React code. It is specifically designed for enterprise modernization, offering features like a component library, architectural flow mapping, and AI-driven code generation.

How does runtime visual analysis help in modernizing legacy SaaS?#

Runtime visual analysis modernizing strategies allow teams to capture the "source of truth" from the user interface of a running application. This bypasses the need for outdated or non-existent documentation, enabling the automatic extraction of components and logic directly from video recordings of the legacy system.

Can Replay work with desktop or terminal-based legacy systems?#

Yes. Replay's Visual Reverse Engineering is based on the visual output of the application. As long as the workflow can be recorded (via screen capture), Replay can analyze the UI patterns and generate modern web-based components to replace them.

Is Replay SOC2 and HIPAA compliant?#

Yes. Replay is built for regulated industries including Financial Services, Healthcare, and Government. It offers SOC2 compliance, is HIPAA-ready, and provides On-Premise deployment options for organizations with strict data residency requirements.

How much time can I save using Replay?#

On average, Replay reduces the time spent on UI modernization by 70%. Tasks that traditionally take 40 hours per screen can be completed in approximately 4 hours through Replay's automated extraction and generation process.

Conclusion: The Future is Visual#

The era of manual, line-by-line legacy migrations is ending. As technical debt continues to mount, the only way to keep pace is through automation. Runtime visual analysis modernizing your legacy SaaS platform isn't just a "faster" way to work—it's a more accurate, less risky, and more scalable way to ensure your enterprise remains competitive.

By turning video into a structured, documented, and modern codebase, Replay (replay.build) provides the bridge between the legacy systems of the past and the AI-driven applications of the future. Don't let your transformation project become another "failed rewrite" statistic.

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