Algorithm Recapture: How to Reverse Engineer Pricing Engines Without Source Access

Your most critical business logic is likely trapped inside a compiled binary from 2004. For financial services and insurance giants, the pricing engine—the "black box" that determines premiums, interest rates, or discount tiers—is often the single biggest hurdle to modernization. When the source code is lost, the original developers have retired, and the documentation is non-existent, you face a terrifying choice: leave the legacy system running on life support or risk a multi-million dollar rewrite that will likely fail.

According to Replay's analysis, 67% of legacy systems lack any form of usable documentation, and 70% of enterprise-scale legacy rewrites fail to meet their original objectives or timeline. The traditional approach to extracting this logic—manual forensic analysis—is a recipe for disaster.

Instead, a new methodology has emerged: Algorithm Recapture. By using visual reverse engineering to observe the runtime behavior of these systems, architects can reconstruct complex logic without ever seeing a single line of the original COBOL, Delphi, or VB6 source code.

TL;DR:

• •The Problem: Mission-critical pricing logic is often "locked" in undocumented legacy systems with no source access.
• •The Solution: Use Algorithm Recapture via Replay to record UI workflows and automatically generate documented React components and logic.
• •The Impact: Reduce modernization timelines from 18 months to weeks, saving 70% in engineering costs while eliminating technical debt.
• •Key Stat: Manual screen recreation takes ~40 hours; Replay does it in 4 hours.

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The Crisis of the "Black Box" Pricing Engine#

In industries like insurance and banking, the pricing engine isn't just a feature; it is the business. These engines often handle hundreds of variables—age, location, risk profiles, historical data—to output a single, deterministic value. Over decades, these systems have been "patched" to the point where the logic is a tangled web of edge cases.

When you attempt to algorithm recapture reverse engineer these systems manually, you encounter the $3.6 trillion global technical debt problem head-on. You aren't just fighting old code; you're fighting the "Ghost in the Machine"—logic that exists in production but nowhere else.

Visual Reverse Engineering is the process of using AI-driven screen recording and state analysis to map user inputs to system outputs, effectively "learning" the underlying business rules through observation rather than code reading.

Industry experts recommend moving away from "Big Bang" rewrites, which average an 18-month timeline for enterprise-grade applications. Instead, by focusing on recapturing the logic through the UI, teams can build a "Shadow Engine" that runs alongside the legacy system to validate accuracy before a full cutover.

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Why Manual Reverse Engineering Fails#

Before we look at the automated solution, it is important to understand why the manual path is a death march. To algorithm recapture reverse engineer a pricing engine manually, an architect must:

1. •Observe: Watch a subject matter expert (SME) enter data.
2. •Hypothesize: Guess the mathematical relationship between input A and output B.
3. •Document: Create a Jira ticket or Word doc (which will be out of date by Tuesday).
4. •Code: Ask a developer to recreate the logic in a modern stack like React or Node.js.
5. •Validate: Compare the new output to the old output.

This process takes an average of 40 hours per screen/workflow. With Replay, that time is slashed to 4 hours.

Comparison: Manual vs. Replay Visual Reverse Engineering#

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The Methodology of Algorithm Recapture#

To effectively algorithm recapture reverse engineer a pricing engine, you need a platform that understands the relationship between DOM changes (or pixel changes in desktop apps) and state transitions. Replay provides this through its AI Automation Suite.

Step 1: High-Fidelity Recording#

The process begins by recording an SME performing a series of exhaustive workflows. This isn't a simple "loom" video; it's a data-rich capture of every state change, input validation, and API call (if applicable).

Step 2: State Mapping#

Replay’s "Flows" feature maps the user journey. It identifies that when "Property Age" is set to >50, the "Premium" field increments by exactly 12.5%. This is the core of algorithm recapture reverse engineer—identifying the mathematical ghosts within the UI.

Step 3: Component Generation#

Once the patterns are identified, Replay generates a documented React component. This isn't just "spaghetti code" generated by a basic LLM. It's a structured, typed component that mirrors the original system's behavior but uses modern best practices.

Video-to-code is the process of converting a visual recording of a software interface into functional, production-ready source code using machine learning and computer vision.

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Implementation: From Legacy UI to React Logic#

Let's look at how we might translate a legacy pricing engine's logic into a modern TypeScript interface after an algorithm recapture reverse engineer session.

Legacy Perspective (The "Black Box")#

Imagine a 1998 PowerBuilder application. We see a field

and a button . We don't have the source, but through Replay, we've observed the following pattern:

• •Base Rate: $500
• •If
  text

  Age
  < 25: +$200
• •If
  text

  Claims
  > 0: + (Base * 0.15)

The Recaptured TypeScript Logic#

Replay generates the logic layer that can be plugged into a modern React frontend.

typescript
// Generated via Replay Algorithm Recapture
interface PricingInputs {
  baseRate: number;
  driverAge: number;
  claimHistoryCount: number;
  regionFactor: 'urban' | 'suburban' | 'rural';
}

export const calculatePremium = (inputs: PricingInputs): number => {
  let total = inputs.baseRate;

  // Recaptured Logic: Age Surcharge
  if (inputs.driverAge < 25) {
    total += 200;
  }

  // Recaptured Logic: Risk Multiplier
  if (inputs.claimHistoryCount > 0) {
    total += (total * 0.15);
  }

  // Recaptured Logic: Geographic Adjustments
  const regionMultipliers = {
    urban: 1.2,
    suburban: 1.0,
    rural: 0.8
  };

  return total * regionMultipliers[inputs.regionFactor];
};

The Modernized React Component#

Beyond the math, Replay builds the UI layer, ensuring that the new system "feels" familiar to users but operates on a modern Design System. For more on this, see our article on Building Design Systems from Legacy Apps.

tsx
import React, { useState, useEffect } from 'react';
import { calculatePremium } from './logic/pricingEngine';
import { Button, Input, Card } from '@/components/ui';

export const PricingModule: React.FC = () => {
  const [age, setAge] = useState<number>(0);
  const [claims, setClaims] = useState<number>(0);
  const [result, setResult] = useState<number | null>(null);

  const handleCalculate = () => {
    const premium = calculatePremium({
      baseRate: 500,
      driverAge: age,
      claimHistoryCount: claims,
      regionFactor: 'urban'
    });
    setResult(premium);
  };

  return (
    <Card title="Recaptured Pricing Engine">
      <div className="space-y-4">
        <Input 
          label="Driver Age" 
          type="number" 
          onChange={(e) => setAge(Number(e.target.value))} 
        />
        <Input 
          label="Claims History" 
          type="number" 
          onChange={(e) => setClaims(Number(e.target.value))} 
        />
        <Button onClick={handleCalculate}>Calculate Premium</Button>
        {result && <div className="text-xl font-bold">Total: ${result.toFixed(2)}</div>}
      </div>
    </Card>
  );
};

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Scaling with Replay: The Library and Blueprints#

When you algorithm recapture reverse engineer at an enterprise scale, you aren't just doing it for one screen. You are doing it for thousands. This is where Replay’s infrastructure becomes essential.

1. •The Library: Replay stores your recaptured components in a central Design System. This ensures that every team across your organization is using the same "Source of Truth" for recaptured logic.
2. •Flows: This feature visualizes the architecture of your legacy system. It allows architects to see the "spaghetti" and untangle it visually before the first line of new code is even written.
3. •Blueprints: This is the visual editor where you can tweak the recaptured logic. If the AI identifies a pattern but a Subject Matter Expert knows there’s a specific regulatory exception, you can modify the blueprint directly.

According to Replay's analysis, using a centralized library for recaptured components reduces "UI Drift" by 85% compared to manual rewrites. Learn more about Replay's Library features.

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The "Shadow Migration" Strategy#

Once you have used Replay to algorithm recapture reverse engineer your pricing engine, industry experts recommend a "Shadow Migration."

In this phase, both the legacy engine and the new Replay-generated engine run simultaneously. For every transaction, the inputs are sent to both engines. If the outputs match 100% over a period of 30 days, the legacy system can be safely decommissioned. This eliminates the risk of "hidden logic" that manual documentation often misses.

Why Visual Data Trumps Source Code#

Source code tells you what the program should do. Visual data tells you what the program actually does. In many legacy systems, the source code might include unused functions, dead branches, or environment-specific hacks that no longer apply. By using Replay to algorithm recapture reverse engineer based on runtime behavior, you ensure you are only modernizing what is currently providing value to the business.

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Security and Compliance in Regulated Industries#

For Financial Services, Healthcare, and Government, security isn't an afterthought. Replay is built for these high-stakes environments.

• •SOC2 & HIPAA Ready: Your data is protected throughout the recapture process.
• •On-Premise Availability: For organizations that cannot use cloud-based AI, Replay offers on-premise deployments to ensure that sensitive pricing algorithms never leave your network.

For more information on secure modernization, check out our guide on Modernizing Regulated Systems.

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Frequently Asked Questions#

What happens if the legacy system has no API?#

Replay does not require an API to function. Because it uses visual reverse engineering, it captures the logic by observing the UI and the underlying DOM/state changes. This makes it the ideal tool to algorithm recapture reverse engineer systems that are completely disconnected from modern infrastructure.

How accurate is the recaptured logic compared to the original?#

According to Replay's analysis, the AI-driven recapture process achieves 99.8% accuracy in deterministic systems. By recording multiple edge-case scenarios, the system can triangulate the exact mathematical formulas used by the legacy engine.

Can Replay handle complex, multi-step workflows?#

Yes. Replay’s "Flows" feature is specifically designed to handle long-running processes that span multiple screens and tabs. It maintains state consistency across the entire journey, ensuring that the recaptured React components function as a cohesive application rather than a collection of isolated screens.

Do I need to be a developer to use Replay?#

While the output is developer-centric (React, TypeScript, CSS), the capture process can be performed by anyone. Subject Matter Experts (SMEs) or Business Analysts can record the workflows, and Replay’s AI Automation Suite handles the heavy lifting of generating the code and documentation.

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Conclusion: The End of Technical Debt#

The $3.6 trillion technical debt crisis exists because we’ve been trying to solve the problem with the same tools that created it. Manual rewrites are slow, expensive, and prone to the same human errors that made the legacy systems "black boxes" in the first place.

By choosing to algorithm recapture reverse engineer your mission-critical engines, you are choosing a data-driven path to modernization. Replay transforms the visual history of your application into the foundation of its future. You don't need the source code to move forward; you just need to see where you've been.

Ready to modernize without rewriting? Book a pilot with Replay and see how we can turn your legacy recordings into production-ready React code in days, not years.