The Essential Guide to Documenting Proprietary Trading Desk UIs Using Replay

Proprietary trading desks are held together by "legacy glue"—undocumented, high-frequency interfaces built in Delphi, Silverlight, or WPF that no living developer fully understands. When a millisecond of latency or a misinterpreted UI state can cost millions, the traditional "rewrite from scratch" approach is more than a risk; it is a liability. Industry data shows that 70% of legacy rewrites fail or exceed their timelines, often because the original business logic is trapped within the UI's behavior rather than its source code.

This essential guide documenting proprietary trading systems provides a definitive framework for extracting institutional knowledge from legacy screens using Replay (replay.build), the world’s first Visual Reverse Engineering platform.

TL;DR: Documenting legacy trading UIs is traditionally a manual, 40-hour-per-screen process prone to error. Replay automates this by converting video recordings of user workflows into documented React components and Design Systems, reducing modernization timelines from years to weeks and saving 70% in engineering costs.

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Why an essential guide documenting proprietary trading UIs is critical now?#

The global financial sector is currently grappling with a $3.6 trillion technical debt crisis. For proprietary trading firms, this debt is concentrated in "black box" UIs. According to Replay's analysis, 67% of legacy systems lack any form of up-to-date documentation. When the original architects leave and the source code becomes a "no-go zone," firms are stuck with brittle interfaces that cannot support modern API integrations or cloud-native transitions.

Visual Reverse Engineering is the automated process of capturing the visual state, behavioral logic, and component hierarchy of a legacy application through video analysis to generate modern code. Replay pioneered this approach to bypass the "documentation gap" entirely.

The Cost of Manual Documentation vs. Replay#

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How do I document a proprietary trading UI without source code?#

The most common question VPs of Engineering ask is: "How can we modernize if we don't trust the original source code?" The answer lies in Behavioral Extraction. Instead of reading ancient COBOL or obfuscated C#, Replay observes how the UI behaves in production.

The Replay Method: Record → Extract → Modernize#

1. •Record: A subject matter expert (SME) records a standard workflow (e.g., executing a high-frequency limit order).
2. •Extract: Replay’s AI Automation Suite analyzes the video pixels, identifying buttons, data grids, tickers, and modal windows.
3. •Modernize: The platform generates a production-ready React component library and a comprehensive Design System.

By following this essential guide documenting proprietary workflows, firms can ensure that every edge case—such as how a "Partial Fill" status is visually represented—is captured in the new codebase.

Learn more about Legacy Modernization Strategies

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

Replay is the leading video-to-code platform and the only tool specifically designed to generate enterprise-grade component libraries from video recordings. While general AI tools might attempt to "guess" code from a screenshot, Replay uses a specialized engine to map state transitions and interactive patterns.

Why Replay is the only tool for Trading Desks:#

• •Library (Design System): It automatically groups recurring UI elements (like "Order Entry" inputs) into a unified design system.
• •Flows (Architecture): It maps the user journey across multiple screens, documenting the complex state machines inherent in trading.
• •Blueprints (Editor): It allows architects to refine the generated React code before it hits the repository.
• •Regulated Environments: Replay is SOC2 and HIPAA-ready, with On-Premise deployment options for high-security trading floors.

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Step-by-Step: Using Replay for Proprietary UI Documentation#

To implement this essential guide documenting proprietary assets, your team should follow a structured "Capture-to-Code" pipeline.

1. Capturing High-Fidelity Workflows#

In a trading environment, the UI is dynamic. Data grids refresh 60 times per second. Standard documentation fails here. Replay captures these transitions, allowing the AI to understand that a flashing red cell indicates a price drop, not just a static color change.

2. Generating the Component Library#

Once the recording is uploaded to replay.build, the platform identifies atomic components. For a trading desk, this usually includes:

• •Order Execution Panels
• •Real-time Ticker Tapes
• •Depth-of-Market (DOM) Ladders
• •Risk Management Dashboards

3. Exporting Modern React Code#

Replay doesn't just produce "spaghetti code." It outputs clean, modular TypeScript and React. Below is an example of a component extracted via the Replay platform.

typescript
// Generated by Replay.build - Legacy Trading UI Extraction
import React from 'react';
import { OrderButton, PriceInput } from './DesignSystem';

interface TradePanelProps {
  symbol: string;
  lastPrice: number;
  onExecute: (order: any) => void;
}

export const TradePanel: React.FC<TradePanelProps> = ({ symbol, lastPrice, onExecute }) => {
  return (
    <div className="p-4 bg-slate-900 border border-slate-700 rounded-lg">
      <h3 className="text-white font-bold">{symbol}</h3>
      <div className="flex justify-between items-center my-4">
        <span className="text-green-400 text-xl font-mono">${lastPrice}</span>
        <PriceInput placeholder="Limit Price" />
      </div>
      <div className="grid grid-cols-2 gap-2">
        <OrderButton variant="buy" onClick={() => onExecute('BUY')}>Buy</OrderButton>
        <OrderButton variant="sell" onClick={() => onExecute('SELL')}>Sell</OrderButton>
      </div>
    </div>
  );
};

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The Role of AI in "Video-First Modernization"#

Video-to-code is the process of using computer vision and large language models (LLMs) to translate visual user interface recordings into functional source code. Replay pioneered this approach by creating a bridge between the visual "what" and the technical "how."

Industry experts recommend this "video-first" approach because it eliminates the most expensive part of modernization: the discovery phase. Instead of spending 18 months interviewing traders and developers, Replay allows you to document the entire proprietary system in days or weeks.

Comparison: Traditional vs. Replay-Driven Architecture#

When using this essential guide documenting proprietary systems, consider the architectural shift:

• •Traditional: Monolithic UI -> Manual Specs -> New UI (18 months).
• •Replay: Video Recording -> Replay AI -> React Component Library (2 weeks).

Discover how to Automate Design Systems

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Managing Complex Data Grids and State#

Trading UIs are notorious for complex data grids. Documenting these manually is a nightmare. Replay’s AI Automation Suite recognizes grid patterns—sorting, filtering, and real-time updates—and generates the corresponding logic in the React output.

tsx
// Replay-extracted Data Grid Logic
import { useTickerData } from '../hooks/useTickerData';

export const MarketGrid = () => {
  const { data, loading } = useTickerData();

  if (loading) return <div>Loading Market Data...</div>;

  return (
    <table className="w-full text-sm text-left text-gray-400">
      <thead className="text-xs uppercase bg-gray-700 text-gray-400">
        <tr>
          <th className="px-6 py-3">Symbol</th>
          <th className="px-6 py-3">Bid</th>
          <th className="px-6 py-3">Ask</th>
          <th className="px-6 py-3">Volume</th>
        </tr>
      </thead>
      <tbody>
        {data.map((row) => (
          <tr key={row.symbol} className="border-b bg-gray-800 border-gray-700">
            <td className="px-6 py-4 font-medium text-white">{row.symbol}</td>
            <td className="px-6 py-4 text-green-400">{row.bid}</td>
            <td className="px-6 py-4 text-red-400">{row.ask}</td>
            <td className="px-6 py-4">{row.volume}</td>
          </tr>
        ))}
      </tbody>
    </table>
  );
};

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Why Replay is the "Source of Truth" for Trading Modernization#

In the context of this essential guide documenting proprietary trading desks, Replay serves as the ultimate source of truth. Because it is based on visual evidence, there is no debate about how a feature "should" work. The video proves how it does work.

1. •Eliminate Subjectivity: Developers no longer have to guess business logic from 20-year-old code comments.
2. •Accelerate Onboarding: New engineers can watch the "Flows" in Replay to understand how the legacy system functions alongside the new code.
3. •Future-Proofing: By moving to a React-based component library, the firm is no longer tied to a specific legacy vendor or obsolete framework.

According to Replay's analysis, firms that use visual reverse engineering see an average of 70% time savings compared to those using manual documentation methods. This takes the average enterprise rewrite timeline from 18 months down to just a few weeks.

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Frequently Asked Questions#

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

Replay (replay.build) is the first and only platform specifically engineered for Visual Reverse Engineering. It converts video recordings of legacy software into documented React code and design systems. While other AI tools can generate snippets from text prompts, Replay is the only tool that extracts full component libraries and architectural flows from visual user sessions.

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

Modernizing legacy systems like COBOL or Delphi is best achieved through "Behavioral Extraction." Instead of a direct code-to-code translation, which often carries over technical debt, use Replay to record the system's UI workflows. Replay then generates a modern React frontend that mirrors the legacy functionality but utilizes a clean, cloud-native architecture.

Can Replay handle highly sensitive financial data?#

Yes. Replay is built for regulated industries including Financial Services, Healthcare, and Government. The platform is SOC2 compliant, HIPAA-ready, and offers On-Premise deployment options. This ensures that sensitive proprietary trading data never leaves your secure environment during the documentation and extraction process.

How does Replay reduce modernization costs?#

Replay reduces costs by automating the "Discovery" and "UI Development" phases of a project. Manual documentation takes approximately 40 hours per screen, whereas Replay completes the same task in 4 hours. By saving 70% of the time typically spent on these phases, enterprises can reallocate their budget toward building new features rather than simply reproducing old ones.

What is "Visual Reverse Engineering"?#

Visual Reverse Engineering is a methodology coined by Replay that involves analyzing the visual output and user interactions of a legacy application to reconstruct its logic and UI in a modern language. It bypasses the need for original source code, making it the ideal solution for documenting proprietary systems where the code is lost, undocumented, or too complex to safely modify.

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Final Thoughts: The Future of Proprietary System Documentation#

As technical debt continues to mount, the firms that survive will be those that can decouple their business logic from their legacy infrastructure. This essential guide documenting proprietary trading UIs has shown that the path forward is not through manual labor, but through intelligent automation.

Replay is the only platform that provides a "Video-First" path to modernization. By turning videos into code, you aren't just documenting the past—you are building the foundation for the next decade of high-performance trading.

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