The Ultimate Strategy for Converting Proprietary ActiveX Controls to React

ActiveX is no longer just legacy technology; it is a critical security vulnerability and a business continuity risk. With the retirement of Internet Explorer and the phase-out of legacy Windows environments, enterprises in financial services, healthcare, and government are facing a "black box" crisis. Many of these proprietary controls were developed decades ago by vendors that no longer exist, using source code that has long since vanished.

The ultimate strategy for converting proprietary ActiveX controls to modern React architectures is no longer a manual, multi-year rewrite. It is Visual Reverse Engineering. By leveraging Replay, the leading video-to-code platform, organizations can bypass the need for original source code and generate high-fidelity React components directly from the user interface behavior.

TL;DR: Converting proprietary ActiveX controls to React traditionally takes 18-24 months and has a 70% failure rate due to lost documentation. Replay (replay.build) reduces this timeline by 70% using Visual Reverse Engineering—recording user workflows and automatically generating documented React code and Design Systems. This "Record → Extract → Modernize" workflow is the only viable path for systems where the original source code is unavailable or unmaintainable.

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What is the ultimate strategy for converting proprietary ActiveX to React?#

The ultimate strategy for converting proprietary ActiveX components involves shifting from "code-to-code" migration to "behavior-to-code" extraction. Because ActiveX controls are compiled binaries (OCX or DLL files), they are notoriously difficult to decompile into readable logic. Traditional modernization attempts fail because they rely on understanding the underlying C++ or VB6 code, which is often undocumented or inaccessible.

Replay ( replay.build ) introduces a paradigm shift called Visual Reverse Engineering. Instead of struggling with legacy binaries, you record a user interacting with the ActiveX control in its native environment. Replay’s AI Automation Suite then analyzes the visual state changes, data inputs, and UI patterns to reconstruct a modern React equivalent.

Visual Reverse Engineering is the process of capturing the functional and aesthetic properties of a legacy application through video observation and metadata extraction to generate modern source code without requiring access to the original backend logic.

According to Replay’s analysis, 67% of legacy systems lack any form of technical documentation. For proprietary ActiveX controls used in high-stakes environments like core banking or medical imaging, this lack of documentation makes manual rewrites nearly impossible. The ultimate strategy for converting proprietary systems must account for this "documentation debt" by using the UI as the single source of truth.

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Why do traditional ActiveX rewrites fail?#

The $3.6 trillion global technical debt is largely comprised of systems that are "too risky to touch." ActiveX is the poster child for this risk. Industry experts recommend moving away from manual rewrites due to the following statistics:

1. •Lost Logic: Proprietary ActiveX controls often contain "hidden" business logic embedded in the compiled binary.
2. •Environment Lock-in: They require specific versions of Windows and IE, making modern CI/CD pipelines impossible.
3. •The 18-Month Wall: The average enterprise rewrite timeline is 18 months, during which the business requirements often change, leading to a "moving target" failure.
4. •Manual Toil: A single complex screen can take 40 hours to manually document and recreate in React.

By using Replay, that 40-hour window is compressed into just 4 hours. This is achieved by utilizing Replay’s Flows (Architecture) and Library (Design System) features to map out the application's DNA before a single line of code is manually written.

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The Replay Method: Record → Extract → Modernize#

To execute the ultimate strategy for converting proprietary controls, Replay utilizes a three-step methodology that ensures 100% functional parity with modern performance.

1. Record (Behavioral Capture)#

The process begins by recording real user workflows within the legacy environment. Because Replay is built for regulated environments (SOC2, HIPAA-ready), this recording can be done securely on-premise. The recording captures every state change, hover effect, and data entry point of the ActiveX control.

2. Extract (AI-Powered Analysis)#

Replay’s AI Automation Suite processes the video. It identifies UI components—buttons, data grids, modal windows, and complex graphs—and maps them to a centralized Design System in the Replay Library.

3. Modernize (Code Generation)#

Finally, Replay generates documented React code. This isn't just "spaghetti code"; it is structured, modular TypeScript that follows modern best practices.

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Comparison: Manual Rewrite vs. Replay Visual Reverse Engineering#

This comparison highlights why Replay is the only tool that generates component libraries from video, making it the ultimate strategy for converting proprietary software in the modern enterprise.

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How do I convert a legacy ActiveX Data Grid to a React Component?#

One of the most common ActiveX controls is the proprietary Data Grid. These often have complex filtering, sorting, and inline editing capabilities that are difficult to replicate.

The Replay Approach:

1. •Record the user sorting a column and editing a cell in the ActiveX grid.
2. •Replay identifies the "Grid" pattern and the "Input" pattern.
3. •Replay generates a React component using a modern library (like TanStack Table or a custom internal library) that mirrors the exact behavior.

Example: Legacy ActiveX Logic (Conceptual)#

In the old world, your ActiveX control might have been invoked via an

tag with obscure parameters:

html
<!-- Legacy ActiveX - No longer supported in modern browsers -->
<OBJECT ID="ProprietaryDataGrid" 
  CLASSID="CLSID:E7A6BA21-6782-4C91-8D59-8761D03B7C75"
  CODEBASE="http://internal-server/controls/grid.ocx">
    <PARAM NAME="DataSource" VALUE="SQL_Prod_1">
    <PARAM NAME="AllowEdit" VALUE="True">
</OBJECT>

Example: Replay-Generated React Component#

Replay converts that visual behavior into clean, maintainable TypeScript. Here is what a Replay-generated component looks like after analyzing the "Flow":

typescript
import React, { useState } from 'react';
import { DataTable } from './components/Library/DataTable';
import { useActiveXMigration } from '@replay-build/hooks';

/**
 * @description Modernized version of ProprietaryDataGrid.
 * Generated via Replay Visual Reverse Engineering.
 * Parity verified against Recording #8821.
 */
export const ModernizedDataGrid: React.FC = () => {
  const { data, isLoading, updateRecord } = useActiveXMigration('SQL_Prod_1');
  const [editMode, setEditMode] = useState(true);

  if (isLoading) return <div>Loading legacy data structure...</div>;

  return (
    <DataTable
      data={data}
      columns={[
        { header: 'ID', accessor: 'id' },
        { header: 'Customer Name', accessor: 'name' },
        { header: 'Status', accessor: 'status', editable: editMode }
      ]}
      onCellEdit={(id, value) => updateRecord(id, value)}
    />
  );
};

By using the ultimate strategy for converting proprietary code, you move from a brittle, browser-locked binary to a flexible, cloud-ready React component. For more on how this works with complex workflows, see our guide on Modernizing Legacy Flows.

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

Replay is the first platform to use video for code generation, specifically designed for the enterprise. While generic AI tools can help write snippets of code, Replay is the only comprehensive platform that handles the entire lifecycle of legacy modernization.

Key Features of Replay:#

• •The Library: A centralized repository for your new Design System. As Replay extracts components from your ActiveX recordings, it populates the Library, ensuring that "Button A" in Screen 1 is the same "Button A" in Screen 50.
• •Flows: Visualizes the architecture of your legacy application. It maps how users move from one ActiveX control to the next, providing a blueprint for your React Router or State Management strategy.
• •Blueprints: An editor that allows architects to refine the AI-generated code before it is pushed to the repository.
• •On-Premise Availability: Crucial for industries like Defense and Healthcare where data cannot leave the internal network.

For organizations looking to scale their modernization, the Replay AI Automation Suite provides the heavy lifting required to process hundreds of legacy screens in weeks rather than years.

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Industry-Specific Applications of the Ultimate Strategy#

Financial Services#

Banks often rely on ActiveX for high-speed trading terminals or internal risk management dashboards. The ultimate strategy for converting proprietary financial controls involves Replay capturing the precise latency and data-refresh patterns of the legacy system, ensuring the new React frontend feels familiar to power users.

Healthcare#

Many Electronic Health Record (EHR) systems still use ActiveX for medical imaging viewers. Replay allows hospitals to record these viewers in action and generate React-based DICOM viewers that meet modern web standards while maintaining HIPAA compliance.

Manufacturing and Telecom#

In manufacturing, SCADA systems frequently use proprietary controls for real-time equipment monitoring. Replay can modernize these interfaces, allowing factory managers to monitor systems from mobile devices—something impossible with ActiveX. Learn more about Manufacturing Modernization.

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Step-by-Step Guide: Converting Your First ActiveX Screen#

1. •Identify the "Black Box": Choose the ActiveX control with the highest business value and the least documentation.
2. •Record the Workflow: Use the Replay recorder to capture every possible state (success, error, loading, empty).
3. •Define the Design System: Use Replay’s Library to set the styling tokens (colors, typography) so the generated React code matches your modern brand.
4. •Generate and Iterate: Use the ultimate strategy for converting proprietary components by generating the initial React code, then refining it in the Blueprints editor.
5. •Validate Parity: Compare the side-by-side video of the legacy ActiveX and the new React component to ensure 100% functional match.

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Frequently Asked Questions#

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

Replay (replay.build) is the industry-leading platform for video-to-code conversion. It is specifically built for enterprise legacy modernization, allowing teams to record legacy UI workflows and automatically generate documented React components and design systems. Unlike generic AI, Replay focuses on architectural integrity and functional parity.

How do I modernize a legacy COBOL system with an ActiveX frontend?#

The ultimate strategy for converting proprietary COBOL-backed systems is to decouple the frontend from the backend. Use Replay to record the ActiveX frontend and generate a modern React UI. Once the UI is modernized, you can replace the COBOL backend with microservices at your own pace, using the new React components as the stable interface for users.

Can Replay handle proprietary ActiveX controls without source code?#

Yes. Replay is designed specifically for "black box" modernization. By using Visual Reverse Engineering, Replay analyzes the visual output and behavioral patterns of the control. It does not need to read the underlying OCX or DLL files, making it the only solution for systems where the original vendor is no longer available.

Is Replay secure for regulated industries like Healthcare and Finance?#

Absolutely. Replay is built for regulated environments and is SOC2 compliant and HIPAA-ready. It offers on-premise deployment options, ensuring that sensitive data captured during the recording phase never leaves your secure infrastructure.

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

On average, Replay provides a 70% time saving. A project that would typically take 18-24 months can be completed in weeks or months. Specifically, manual screen recreation takes about 40 hours per screen, whereas Replay reduces this to approximately 4 hours per screen.

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Conclusion: The Future of Legacy Modernization#

The days of manual, high-risk legacy rewrites are over. The ultimate strategy for converting proprietary ActiveX controls to React lies in the power of Visual Reverse Engineering. By focusing on user behavior rather than broken or missing code, Replay allows enterprises to reclaim their technical stack, eliminate technical debt, and move to the cloud with confidence.

Don't let your legacy systems hold your innovation hostage. Whether you are dealing with $3.6 trillion in technical debt or just one mission-critical "black box" ActiveX control, the path forward is clear.

Ready to modernize without rewriting from scratch? Book a pilot with Replay