COBOL to React: Modernizing Insurance Claims Adjudication Using Video-First Documentation

$3.6 trillion. That is the estimated global cost of technical debt currently paralyzing enterprise organizations. For the insurance industry, this debt isn't just a line item on a balance sheet; it’s buried in millions of lines of COBOL code powering claims adjudication systems that haven't been fully documented since the Reagan administration.

When a VP of Engineering at a Tier-1 carrier decides to move from cobol to react, they aren't just changing a syntax—they are attempting a heart transplant on a moving patient. The traditional "Big Bang" rewrite is the primary reason why 70% of legacy modernization projects fail or exceed their timelines by years. The problem isn't the destination (React); it's the "archaeology" required to understand the point of origin (COBOL).

TL;DR: Modernizing insurance claims systems from COBOL to React fails when teams prioritize rewriting over understanding; Replay’s visual reverse engineering reduces migration time by 70% by using video as the ultimate source of truth for business logic.

The $3.6 Trillion Bottleneck: Why Insurance Claims Modernization Stalls#

Insurance claims adjudication is arguably the most complex logic-dense environment in the enterprise. A single claim might pass through hundreds of validation checks, regulatory compliance filters, and historical lookup tables—all written in COBOL and accessed via 3270 "green screen" emulators.

The industry standard for moving from cobol to react has historically been manual discovery. This involves hiring expensive consultants to sit with claims adjusters, take notes on their workflows, and then attempt to find the corresponding logic in a codebase where 67% of the systems lack updated documentation. This "archaeology" phase alone typically consumes 30-40% of the project budget before a single line of React is even written.

The Failure of the "Big Bang" Rewrite#

The "Big Bang" approach—where you attempt to replicate the entire system in a modern stack from scratch—is a recipe for disaster in regulated environments.

⚠️ Warning: Attempting a COBOL to React migration without a verified business logic map usually results in "logic drift," where the new system fails to handle edge cases that the legacy system managed perfectly for decades.

Visual Reverse Engineering: The Replay Paradigm#

The future of legacy modernization isn't rewriting from scratch—it's understanding what you already have. At Replay, we’ve pioneered a process called Visual Reverse Engineering. Instead of starting with the COBOL source code (the "Black Box"), we start with the user's reality.

By recording real user workflows within the legacy claims system, Replay captures every state change, every data entry, and every hidden business rule triggered by a claims adjuster. Our AI Automation Suite then analyzes these recordings to generate documented React components and API contracts.

Moving from Black Box to Documented Codebase#

When you record a claims adjudication flow, Replay doesn't just capture a video file. It captures the metadata of the interaction. It sees that when a "Loss Date" is entered before a "Policy Effective Date," the COBOL backend triggers an error. Replay documents that logic and prepares it for the React frontend.

💰 ROI Insight: Manual documentation takes an average of 40 hours per screen. With Replay’s automated extraction, that time is slashed to 4 hours per screen—a 90% reduction in manual effort.

The Technical Path: COBOL to React Step-by-Step#

Modernizing an insurance claims system requires a surgical approach. You cannot simply "port" COBOL to TypeScript. You must extract the intent and rebuild the interface for the modern web.

Step 1: Assessment and Audit#

Before writing code, you need a technical debt audit. Replay’s platform analyzes your existing workflows to identify which parts of the claims process are most frequently used and which are obsolete. This prevents the common mistake of migrating "dead code" that no longer serves a business purpose.

Step 2: Recording the Source of Truth#

Subject Matter Experts (SMEs) perform their daily tasks—processing a claim, adjusting a payout, or flagging fraud—while Replay records the session. This video becomes the "Source of Truth." It eliminates the "he-said-she-said" between the business units and the engineering team.

Step 3: Blueprinting and Extraction#

Replay’s Blueprints editor takes the recorded session and extracts the underlying architecture. It identifies the data structures required for the React state.

typescript
// Example: Replay-generated TypeScript interface 
// Extracted from a COBOL Claims Adjudication Screen
export interface InsuranceClaim {
  claimId: string;
  policyNumber: string;
  claimantDetails: {
    firstName: string;
    lastName: string;
    ssnLastFour: string;
  };
  lossEvent: {
    date: string; // ISO format converted from COBOL Julian date
    type: 'Auto' | 'Property' | 'Liability';
    description: string;
  };
  status: 'Pending' | 'Approved' | 'Denied' | 'Under_Review';
}

Step 4: Component Generation#

Once the data structures are mapped, Replay generates functional React components that mirror the legacy functionality but utilize a modern Design System.

tsx
// Example: Generated React component from Replay Extraction
import React, { useState } from 'react';
import { Button, Input, Alert } from '@/components/ui';

export function ClaimsAdjudicationForm({ initialData }: { initialData: InsuranceClaim }) {
  const [claim, setClaim] = useState(initialData);
  const [error, setError] = useState<string | null>(null);

  const validateDates = (lossDate: string, policyDate: string) => {
    // Business logic preserved from legacy COBOL validation rule #402
    return new Date(lossDate) >= new Date(policyDate);
  };

  const handleUpdate = (field: keyof InsuranceClaim, value: any) => {
    setClaim(prev => ({ ...prev, [field]: value }));
  };

  return (
    <div className="p-6 bg-white rounded-lg shadow-md">
      <h2 className="text-xl font-bold mb-4">Adjudication: {claim.claimId}</h2>
      <Input 
        label="Loss Date" 
        type="date" 
        value={claim.lossEvent.date}
        onChange={(e) => handleUpdate('lossEvent', { ...claim.lossEvent, date: e.target.value })}
      />
      {/* React logic replacing legacy green-screen alerts */}
      {!validateDates(claim.lossEvent.date, '2023-01-01') && (
        <Alert variant="destructive">Warning: Loss date precedes policy effective date.</Alert>
      )}
      <Button className="mt-4" onClick={() => console.log('Submitting to Modern API...')}>
        Submit Adjudication
      </Button>
    </div>
  );
}

Bridging the Documentation Gap#

67% of legacy systems have no documentation. In the insurance world, this is a massive compliance risk. When moving cobol to react, the documentation is often more important than the code itself for SOC2 and HIPAA-ready environments.

Replay automatically generates:

• •API Contracts: Define exactly how the new React frontend should talk to the remaining mainframe services or new microservices.
• •E2E Tests: Replay uses the recorded video to generate Playwright or Cypress tests, ensuring the new system behaves exactly like the old one.
• •Visual Flows: A map of how a user moves from "Claim Opened" to "Payment Issued," identifying every branch in the logic.

💡 Pro Tip: Don't try to refactor the business logic and migrate the stack at the same time. Use Replay to extract the existing logic into React first, then refactor once you have a stable, documented codebase.

Addressing Security and Compliance in Regulated Industries#

For Financial Services and Insurance, the cloud isn't always an option for sensitive data. Replay is built for these environments. Our platform offers:

• •On-Premise Deployment: Keep your legacy data and recordings within your own firewall.
• •SOC2 & HIPAA Readiness: Automated PII masking ensures that sensitive claimant data is never exposed during the reverse engineering process.
• •Technical Debt Audit: A clear report on what was moved, what was retired, and what remains to be modernized.

The Replay Library: Building a Sustainable Future#

One of the biggest risks of moving from cobol to react is creating "new legacy" code. Without a centralized design system, different teams will build different versions of a "Claim Card" or "Policy Header."

Replay’s Library feature acts as a Design System manager. As components are extracted from the legacy system, they are added to a central repository. This ensures that the next time a team modernizes an insurance module, they aren't starting from zero. They are using pre-verified, documented components that have already been extracted from the legacy environment.

Case Study: From 18 Months to 6 Weeks#

A major insurance carrier recently attempted to modernize their claims intake portal. Their initial estimate for a manual rewrite from cobol to react was 18 months with a team of 12 developers. The primary bottleneck was the 400+ page COBOL "run book" that was 15 years out of date.

By implementing Replay:

1. •They recorded 50 hours of actual claims processing.
2. •Replay identified 120 unique UI components and 45 distinct business rules.
3. •The "Blueprint" was generated in 10 days.
4. •The first functional React prototype was delivered in week 6.

The project didn't just move faster; it was more accurate. The automated E2E tests caught three critical edge cases regarding multi-state tax withholding that the manual discovery team had completely missed.

Frequently Asked Questions#

How does Replay handle COBOL systems with no source code access?#

Replay is platform-agnostic because it uses Visual Reverse Engineering. We don't need to read the underlying COBOL source code to understand the business logic. By capturing the inputs, outputs, and screen changes of the user interface, we can reconstruct the logic and data requirements needed for a React frontend.

Can Replay generate API contracts for mainframe integration?#

Yes. During the extraction process, Replay identifies the data payloads being sent and received by the legacy interface. It can then generate OpenAPI (Swagger) specifications that define the "contract" between your new React application and the legacy backend (or a new middleware layer).

What is the average time savings when moving cobol to react?#

On average, enterprise teams see a 70% reduction in total project time. This is primarily achieved by eliminating the manual "archaeology" and documentation phases, which usually account for the majority of the timeline in legacy projects.

Is the generated React code "clean"?#

Replay generates standard, readable TypeScript and React code. It follows modern best practices, including hooks for state management and modular component architecture. Unlike generic "low-code" tools, the output is a standard codebase that your developers can own, modify, and maintain in their existing CI/CD pipelines.

How does Replay handle complex insurance rules?#

Replay’s AI Automation Suite identifies patterns in user behavior and screen responses. If a certain combination of inputs consistently triggers a specific calculation or error message, Replay flags this as a "Business Rule" in the Blueprint editor. Developers can then verify this logic and ensure it is accurately represented in the new React application.

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Ready to modernize without rewriting? Book a pilot with Replay - see your legacy screen extracted live during the call.