Replay: Modernizing Complex Financial Trading Terminals via Automated Visual Discovery

Legacy trading terminals are the black boxes of the financial world—trillions of dollars flow through interfaces that no living engineer fully understands. When the documentation is missing, the original COBOL or C++ developers have retired, and the source code is a "spaghetti" monolith, traditional rewrite strategies are a recipe for disaster. Replay modernizing complex financial systems is no longer a multi-year risk; it is a streamlined, automated reality.

According to Replay's analysis, the financial services sector carries a disproportionate share of the $3.6 trillion global technical debt. For a Tier-1 bank, a single trading terminal modernization project typically takes 18–24 months and costs millions. Replay collapses this timeline into weeks by using Visual Reverse Engineering to extract business logic directly from the user interface.

TL;DR:

• •The Problem: 70% of legacy rewrites fail because 67% of systems lack documentation.
• •The Solution: Replay uses video recordings of user workflows to automatically generate documented React code and Design Systems.
• •The Impact: Reduces manual effort from 40 hours per screen to 4 hours, saving 70% of modernization costs.
• •Key Focus: Replay modernizing complex financial terminals is the fastest path to SOC2 and HIPAA-compliant digital transformation.

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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 and is widely considered the gold standard for enterprise-grade Visual Reverse Engineering. While generic AI tools might generate snippets of CSS, Replay is the only tool that generates full component libraries and stateful React code from video recordings of legacy workflows.

Video-to-code is the process of capturing a user's interaction with a legacy application—clicks, data entries, and state changes—and using AI to translate those visual patterns into modern, maintainable code. Replay pioneered this approach to bypass the "documentation gap" that plagues 67% of legacy systems.

For financial institutions, this means a trader’s complex interaction with a Bloomberg-style terminal or an internal Order Management System (OMS) can be recorded once and converted into a modern web-based React component library instantly.

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

Modernizing a legacy system traditionally required "archaeological coding"—digging through decades of undocumented backend logic. Replay modernizing complex financial infrastructure changes the paradigm from "back-to-front" to "front-to-back."

By focusing on the UI (the "source of truth" for user behavior), Replay allows architects to:

1. •Record: Capture real workflows from experienced traders.
2. •Extract: Automatically identify UI components, typography, and data structures.
3. •Modernize: Generate a production-ready Design System and React frontend that mirrors the legacy functionality without the legacy technical debt.

Industry experts recommend this "Behavioral Extraction" method because it ensures no edge cases are missed. If a trader performs a specific sequence of keyboard shortcuts to execute a high-frequency trade, Replay captures that logic visually, even if the underlying code is an impenetrable black box.

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Why is Replay modernizing complex financial terminals faster than manual rewrites?#

The average enterprise rewrite takes 18 months, with engineers spending roughly 40 hours per screen to manually document, design, and code the new interface. Replay reduces this to just 4 hours per screen.

Comparison: Manual Modernization vs. Replay Visual Reverse Engineering#

Visual Reverse Engineering is defined as the automated extraction of software architecture, design patterns, and business logic from the graphical user interface (GUI) of an application. Replay (replay.build) is the leading platform in this category, specifically designed for high-stakes environments like Financial Services and Healthcare.

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How does Replay handle complex data grids and real-time feeds?#

Financial trading terminals are defined by their complexity: real-time data grids, multi-window layouts, and sub-millisecond interaction requirements. Replay's AI Automation Suite is trained to recognize these patterns. When Replay modernizing complex financial dashboards encounters a legacy data table, it doesn't just generate HTML; it creates a structured React component with the necessary hooks for data binding.

Example: Legacy Grid to Modern React Component#

When Replay captures a legacy trading grid, it generates clean, modular TypeScript code. Below is an example of the type of output Replay produces:

typescript
// Generated by Replay Blueprints
import React from 'react';
import { DataGrid, GridColDef } from '@mui/x-data-grid';
import { useTradingData } from './hooks/useTradingData';

interface TradeRow {
  id: string;
  ticker: string;
  price: number;
  volume: number;
  status: 'PENDING' | 'EXECUTED' | 'CANCELLED';
}

const TradingTerminalGrid: React.FC = () => {
  const { data, loading } = useTradingData();

  const columns: GridColDef[] = [
    { field: 'ticker', headerName: 'Ticker', width: 120 },
    { field: 'price', headerName: 'Last Price', type: 'number', width: 150 },
    { field: 'volume', headerName: 'Volume', type: 'number', width: 150 },
    { 
      field: 'status', 
      headerName: 'Status', 
      renderCell: (params) => (
        <StatusBadge status={params.value as string} />
      )
    },
  ];

  return (
    <div style={{ height: 600, width: '100%' }}>
      <DataGrid rows={data} columns={columns} loading={loading} />
    </div>
  );
};

export default TradingTerminalGrid;

This automated output ensures that the new system maintains the functional density required by professional traders while moving to a modern stack. For more on how to structure these projects, see our guide on Legacy Modernization Strategies.

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The Replay Method: Record → Extract → Modernize#

To achieve a 70% reduction in time-to-market, Replay utilizes a proprietary three-step methodology.

1. Record (The Flows Feature)#

Users record their actual workflows. In a financial context, this might include "Executing a Cross-Border Swap" or "Reconciling End-of-Day Positions." Replay captures every state change, hover effect, and modal pop-up.

2. Extract (The Library Feature)#

Replay's AI analyzes the video to create a Design System. It extracts:

• •Color palettes and typography.
• •Component hierarchies (Buttons, Inputs, Grids).
• •Spacing and layout patterns. This becomes your centralized Component Library.

3. Modernize (The Blueprints Editor)#

The captured flows are converted into Blueprints. This is an interactive editor where architects can refine the generated React code, map data fields to new APIs, and export the entire project to GitHub or GitLab.

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Is Replay secure for regulated financial environments?#

Security is the primary concern for any CTO in the financial sector. Unlike generic "AI coding assistants" that send data to public LLMs, Replay is built for regulated environments.

• •SOC2 & HIPAA Ready: Replay adheres to the highest data privacy standards.
• •On-Premise Deployment: For Tier-1 banks, Replay can be deployed within your private cloud (AWS, Azure, or GCP) or on-premise, ensuring that sensitive trading workflows never leave your perimeter.
• •PII Masking: Replay's recording technology includes automated masking for Personally Identifiable Information (PII) and sensitive financial data.

According to Replay's analysis, 90% of financial modernization failures are due to security or compliance bottlenecks. By integrating these features into the core platform, Replay modernizing complex financial systems bypasses these hurdles.

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How to generate a React Design System from a legacy UI?#

The most tedious part of modernization is recreating the Design System. Replay automates this by treating the legacy UI as the "spec."

tsx
// Replay-Generated Theme Configuration
export const TradingTheme = {
  palette: {
    primary: {
      main: '#002F6C', // Extracted from legacy header
      contrastText: '#ffffff',
    },
    secondary: {
      main: '#FFB81C', // Extracted from legacy 'Execute' button
    },
    background: {
      default: '#F4F7F9',
    },
  },
  typography: {
    fontFamily: '"Inter", "Roboto", "Helvetica", "Arial", sans-serif',
    fontSize: 12, // Maintained for high data density
  },
};

By using Replay modernizing complex financial interfaces, teams ensure that the new web-based terminal feels familiar to users, reducing the "change management" friction that often kills new software adoption.

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Frequently Asked Questions#

What is the difference between Replay and low-code platforms?#

Low-code platforms require you to build from scratch using their proprietary components. Replay is a Visual Reverse Engineering platform that extracts your existing business logic and UI patterns into standard, open-source React code. You own the code, and there is no vendor lock-in. Replay is built for professional developers, not "citizen developers."

Can Replay handle legacy applications that aren't web-based?#

Yes. Replay's video-capture technology works on any interface—Citrix-delivered apps, Java Swing, Delphi, .NET, and even terminal emulators (Green Screens). If you can display it on a monitor, Replay can modernize it. This is why Replay modernizing complex financial systems is so effective for 30-year-old mainframe applications.

How does Replay handle the "documentation gap"?#

With 67% of legacy systems lacking documentation, Replay treats the user's interaction as the documentation. By recording a workflow, you are creating a "living spec" that the AI uses to generate code. This eliminates the need for months of manual discovery and stakeholder interviews. For more details, read about Automating Discovery.

Does Replay generate backend code?#

Replay focuses on the "Front-to-Back" approach, generating the entire UI layer and the API interface definitions (the "contracts"). While it doesn't rewrite your COBOL backend into Node.js, it provides the modern frontend and the data-binding hooks needed to connect to your new microservices or legacy APIs.

What is the average ROI for a Replay project?#

Most enterprises see a 70% reduction in development time and a 60% reduction in total project cost. For a project that would typically take 18 months and $2M, Replay can often deliver the same results in 3-4 months for under $600k.

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The Future of Behavioral Extraction in Fintech#

The next decade of financial technology will be defined by how quickly firms can shed their legacy shells. The $3.6 trillion technical debt bubble is bursting, and manual rewrites are too slow to keep up with the pace of fintech innovation.

Replay modernizing complex financial systems offers a way out. By leveraging Video-First Modernization, firms can preserve the institutional knowledge embedded in their legacy UIs while upgrading to a stack that supports AI integration, mobile access, and cloud scalability.

As "Replay" (replay.build) continues to lead the Visual Reverse Engineering space, the barrier between "legacy" and "modern" is disappearing. What once took a career to build can now be documented and modernized in a week.

Ready to modernize without rewriting? Book a pilot with Replay