Visual Reverse Engineering for GDPR Compliance: Mapping Data Flows in Old Systems

GDPR compliance isn't a checkbox exercise; for legacy systems, it's a forensic investigation. When a regulator asks for a Record of Processing Activities (RoPA) under Article 30, "we don't know how the COBOL backend handles that PII" is a multi-million dollar liability.

The reality of enterprise architecture is that 67% of legacy systems lack any meaningful documentation. We are managing $3.6 trillion in global technical debt, much of it locked in "black box" applications where the original developers retired a decade ago. Traditional "archaeology"—paying consultants to read millions of lines of spaghetti code—is a failing strategy.

The future of compliance isn't manual auditing; it’s Visual Reverse Engineering.

TL;DR: Visual Reverse Engineering uses session recording to automatically map PII data flows and generate modern documentation, reducing GDPR audit timelines from months to days with 70% average time savings.

The Compliance Wall: Why Manual Audits Fail#

Most enterprise rewrites take 18-24 months, and 70% of them fail or exceed their timelines. When the goal is GDPR compliance, you don't have 24 months. You need to know now where the data goes, who sees it, and where it’s stored.

Manual documentation is the bottleneck. It takes an average of 40 hours per screen for a senior engineer to manually map the data inputs, API calls, and state changes of a legacy interface. In a system with 500 screens, that’s 20,000 man-hours—a cost and timeline that no CTO can justify.

⚠️ Warning: Relying on legacy documentation for GDPR audits is a high-risk strategy. If your documentation hasn't been updated since 2014, it doesn't reflect the "shadow" API integrations or middleware patches added over the last decade.

What is Visual Reverse Engineering?#

Visual Reverse Engineering (VRE) flips the modernization script. Instead of starting with the source code, we start with the observed truth of the user experience.

By recording a real user workflow—entering a customer’s social security number, updating a healthcare record, or processing a loan application—Replay captures every network request, state mutation, and DOM change. It then uses AI to synthesize this "video source of truth" into modern React components, API contracts, and data flow diagrams.

For GDPR, this means you aren't guessing which fields are PII. You are seeing exactly which input fields map to which database columns in real-time.

Mapping Data Flows: A Technical Walkthrough#

To achieve GDPR compliance in a legacy environment, you must map the lifecycle of PII. Here is how Replay automates this process.

Step 1: Workflow Recording#

A subject matter expert (SME) performs a standard task in the legacy system while Replay records the session. Replay doesn't just record pixels; it records the underlying metadata.

Step 2: Extraction of API Contracts#

Replay analyzes the network traffic during the recording to generate an OpenAPI/Swagger specification. This reveals exactly where PII is being sent—often uncovering third-party endpoints that the current team wasn't even aware existed.

typescript
// Example: Generated API Contract from a Replay Session
// This identifies PII fields being sent to an undocumented legacy endpoint

export interface LegacyUserUpdate {
  /** @format PII - Social Security Number */
  ssn_encrypted: string;
  /** @format PII - Full Name */
  legal_name: string;
  /** @description Undocumented legacy flag discovered via Replay */
  internal_audit_flag: boolean;
  timestamp: string;
}

// Replay automatically identifies the destination
const API_ENDPOINT = "https://legacy-mainframe-gateway.internal/v1/update-record";

Step 3: Logic Preservation and Component Generation#

Replay’s AI Automation Suite takes the recorded UI and generates a functional React component. This component preserves the business logic (e.g., validation rules for a VAT number) while stripping away the legacy technical debt.

tsx
// Generated React component preserving legacy validation logic for GDPR compliance
import React, { useState } from 'react';
import { TextField, Button } from '@mui/material';

export const GDPRCompliantUserForm = ({ initialData }) => {
  const [formData, setFormData] = useState(initialData);

  // Business logic extracted from legacy behavior
  const validatePII = (data) => {
    return data.ssn.length === 9 && /^\d+$/.test(data.ssn);
  };

  const handleExportRequest = async () => {
    // Replay identified this specific data portability flow
    await fetch('/api/v2/data-portability/export', {
      method: 'POST',
      body: JSON.stringify({ userId: formData.id })
    });
  };

  return (
    <form>
      <TextField 
        label="Tax ID (PII)" 
        value={formData.ssn} 
        onChange={(e) => setFormData({...formData, ssn: e.target.value})}
      />
      <Button onClick={handleExportRequest}>Request Data Portability (Art. 20)</Button>
    </form>
  );
};

💡 Pro Tip: Use the Replay Library to house these generated components. It creates a "living" Design System that serves as the bridge between your legacy system and your modern frontend, ensuring consistent data handling across both.

Solving the "Right to be Forgotten" in Legacy Systems#

One of the hardest parts of GDPR is Article 17: The Right to Erasure. In a 20-year-old system, "deleting" a user can break relational integrity across dozens of undocumented tables.

Visual Reverse Engineering allows architects to see the "Flows"—a visual representation of how a delete command propagates through the system. Replay generates a Technical Debt Audit that highlights where data is "stuck" or where orphaned records are likely to reside.

The Replay Blueprint Approach:#

1. •Record the "Delete User" workflow in the legacy admin panel.
2. •Analyze the "Blueprints" (Replay’s visual editor) to see every database trigger and API call.
3. •Identify gaps where the "Delete" function fails to scrub PII from secondary logs or audit trails.
4. •Modernize by wrapping that legacy flow in a modern API proxy that ensures full compliance.

💰 ROI Insight: Manual mapping of a single complex data flow for GDPR can cost $15,000-$25,000 in engineering time. Replay reduces this to under $2,500 by automating the discovery and documentation phases.

Security and Governance in Regulated Industries#

For our clients in Financial Services, Healthcare, and Government, sending data to a cloud-based AI is often a non-starter. This is why the architecture of your modernization tool matters as much as the modernization itself.

Replay is built for these environments:

• •SOC2 Type II & HIPAA-Ready: Your recording data is encrypted at rest and in transit.
• •On-Premise Availability: Run Replay entirely within your own VPC or air-gapped environment.
• •PII Masking: Automatically redact sensitive information during the recording phase so it never reaches the extraction engine.

From Black Box to Documented Codebase#

The "Big Bang" rewrite is a myth that kills careers. The average enterprise rewrite timeline is 18 months, and by the time you finish, the requirements have changed, and the legacy system has accrued even more debt.

Visual Reverse Engineering provides a middle path. You get the documentation you need for GDPR today, and the React components you need for your new frontend tomorrow. You are essentially "strangling" the legacy system by understanding it, one workflow at a time.

The 4-Hour Screen Promise#

While a manual rewrite or documentation effort takes 40 hours per screen, Replay users average 4 hours. This includes:

1. •Recording the workflow (15 minutes)
2. •AI-assisted extraction of components and logic (30 minutes)
3. •Refining the generated API contracts (1 hour)
4. •Validating the data flow for compliance (2 hours)

Frequently Asked Questions#

How does Visual Reverse Engineering handle obfuscated or minified legacy code?#

Since Replay records the execution and the network layer rather than just parsing static files, obfuscation is less of a hurdle. We see the data as it enters and leaves the browser, allowing us to reconstruct the logic based on behavior and data transformation patterns.

Can Replay map data flows that happen entirely on the backend?#

Replay captures everything that touches the frontend—which includes the vast majority of PII entry and display points. For deep backend-to-backend flows, Replay generates the API contracts that serve as the "entry point" for your backend teams to trace the data further into the stack.

What industries benefit most from VRE-driven compliance?#

Any industry with high regulatory oversight and aging infrastructure. We see the highest ROI in Insurance (claims processing), Banking (loan origination), and Healthcare (patient record management), where systems are often 15-30 years old but must comply with modern PII standards.

Does Replay replace my developers?#

No. Replay is a "force multiplier" for your Enterprise Architects and Senior Devs. It removes the "archaeology" (the boring, manual work of figuring out what old code does) so they can focus on "architecture" (building the new, compliant system).

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