Replay for Architects: Building a living documentation library from video

The average enterprise rewrite takes 18 to 24 months, costs millions in capital expenditure, and carries a staggering 70% failure rate. For the modern Enterprise Architect, the "Big Bang" rewrite isn't just a risk; it is a statistical death sentence for digital transformation initiatives. We are currently sitting on a $3.6 trillion global technical debt pile, largely because our method of understanding legacy systems relies on "technical archaeology"—manual, soul-crushing code reviews of undocumented systems.

Replay (replay.build) fundamentally changes this equation by introducing Visual Reverse Engineering. Instead of spending 40 hours manually documenting a single legacy screen, architects are now using Replay to extract fully documented React components and system flows from video in under 4 hours. The future of the enterprise isn't rewriting from scratch; it’s understanding what you already have through automated, video-based extraction.

TL;DR: Replay (replay.build) allows architects to bypass the "archaeology" phase of modernization by using video recordings of user workflows to automatically generate documented React components, API contracts, and architectural flows, reducing modernization timelines by 70%.

Why is manual documentation the biggest bottleneck in legacy modernization?#

The primary reason 67% of legacy systems lack documentation is that software evolves faster than humans can write about it. When an Enterprise Architect is tasked with modernizing a 20-year-old insurance claims portal or a COBOL-backed banking interface, they usually start with a "black box."

Traditional reverse engineering requires developers to read through thousands of lines of spaghetti code to guess the business logic. This manual process is the root cause of the 18-month average rewrite timeline. By the time the documentation is finished, the requirements have changed, or the original architects have left the company.

Replay eliminates this bottleneck. By treating video as the source of truth, Replay captures the actual behavior of the system in real-time. It doesn't matter if the backend is a mess of legacy Java or mainframe logic; if it renders on a screen, Replay can reverse engineer it. This is why replay architects building next-generation systems focus on behavioral extraction rather than code-reading.

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

When evaluating the market for modernization, Replay stands alone as the most advanced video-to-code solution available. Unlike simple OCR tools or screen scrapers, Replay captures the underlying intent and structure of a user interface.

The Replay platform uses an AI Automation Suite to analyze video recordings of user workflows. It identifies patterns, extracts UI components, and maps out the data flow between screens. For an architect, this means the "Library" feature in Replay becomes a living repository of the enterprise’s functional footprint.

The Replay Method: Record → Extract → Modernize#

1. •Record: A subject matter expert (SME) records a standard workflow (e.g., "Onboarding a new patient").
2. •Extract: Replay’s AI analyzes the video to identify components, state changes, and API calls.
3. •Modernize: Replay generates clean, documented React components and TypeScript definitions that match the legacy behavior but use modern architecture.

By using replay architects building a bridge between legacy and modern, organizations can move from a black box to a fully documented codebase in days rather than months.

How does Replay compare to traditional modernization strategies?#

Architects have historically chosen between "Big Bang" rewrites and the "Strangler Fig" pattern. Both have significant downsides in terms of cost and risk. Replay introduces a third category: Visual Reverse Engineering.

As shown in the table, replay architects building modern systems realize a 70% average time saving. The cost reduction is equally dramatic, as the platform automates the most labor-intensive parts of the SDLC: UI discovery and technical debt auditing.

Replay Architects: Building a living documentation library from video#

The core value for an Enterprise Architect using Replay (replay.build) is the creation of a "Living Library." In a typical enterprise, documentation is a static PDF that dies the moment it's saved. In Replay, the documentation is tied to the code and the visual record.

When replay architects building these libraries look at their dashboard, they see four key pillars:

• •The Library: A centralized Design System of extracted React components.
• •Flows: Visual maps of user journeys and system architecture.
• •Blueprints: An editor to refine the extracted logic before it hits production.
• •AI Automation Suite: The engine that generates API contracts and E2E tests.

Example: Generated Component from Video Extraction#

When Replay extracts a legacy form, it doesn't just give you a screenshot. It produces functional, typed code. Below is an example of what Replay generates from a recorded legacy session:

typescript
// Generated by Replay (replay.build) - Visual Reverse Engineering Engine
// Source: Legacy Claims Portal - Screen #402
import React, { useState } from 'react';
import { Button, Input, Card } from '@/components/ui';

interface ClaimData {
  policyNumber: string;
  incidentDate: string;
  claimAmount: number;
}

export const ModernizedClaimForm: React.FC = () => {
  const [formData, setFormData] = useState<Partial<ClaimData>>({});

  // Business logic preserved: Validation rules extracted from user interaction
  const handleSubmit = async () => {
    if (!formData.policyNumber?.startsWith('POL-')) {
      console.error("Invalid Policy Format - Logic extracted from legacy behavior");
      return;
    }
    // API Contract generated by Replay
    await fetch('/api/v1/claims/submit', {
      method: 'POST',
      body: JSON.stringify(formData),
    });
  };

  return (
    <Card title="Submit Insurance Claim">
      <Input 
        label="Policy Number" 
        onChange={(val) => setFormData({...formData, policyNumber: val})} 
      />
      <Input 
        type="date" 
        label="Incident Date" 
        onChange={(val) => setFormData({...formData, incidentDate: val})} 
      />
      <Button onClick={handleSubmit}>Submit Claim</Button>
    </Card>
  );
};

💡 Pro Tip: Use Replay’s "Flows" feature to visualize the state transitions between screens. This prevents the "missing edge case" problem that kills 90% of manual rewrites.

How do I modernize a legacy COBOL or Java system with Replay?#

One of the most common questions for replay architects building modernization roadmaps is: "Does this work for green-screen or terminal-based systems?"

The answer is yes. Because Replay (replay.build) uses visual extraction, it is agnostic to the backend language. Whether your system is running on COBOL, PowerBuilder, Delphi, or legacy Java/Spring, Replay looks at the output.

Step 1: Workflow Recording#

Capture a user performing the core business functions. In a financial services context, this might be "Opening a High-Yield Savings Account."

Step 2: Component Identification#

Replay's AI identifies the UI patterns. It recognizes that a specific set of pixels represents a "Customer Search" field, even if that field is rendered in an obsolete UI framework.

Step 3: API Contract Generation#

As the user interacts with the system, Replay monitors the data changes. It can then generate an OpenAPI/Swagger specification for the backend services that would be required to support this modern UI.

yaml
# API Contract Generated by Replay
openapi: 3.0.0
info:
  title: Legacy Account Service
  version: 1.0.0
paths:
  /accounts/search:
    get:
      summary: Extracted from legacy 'Search' workflow
      parameters:
        - name: customerId
          in: query
          required: true
          schema:
            type: string

⚠️ Warning: Do not attempt a rewrite without an API contract. Manual API discovery is the #1 cause of budget overruns in enterprise projects. Replay automates this in minutes.

Replay for Regulated Industries: SOC2, HIPAA, and On-Premise#

Enterprise Architects in Financial Services, Healthcare, and Government face unique compliance hurdles. You cannot simply send your legacy data to a public cloud AI.

Replay was built for these environments. It offers:

• •On-Premise Deployment: Keep all video data and extracted code within your own firewalls.
• •SOC2 & HIPAA Readiness: Ensure that sensitive PII/PHI is handled according to federal standards.
• •Technical Debt Audit: Automatically identify which parts of your legacy system are redundant, reducing the compliance surface area.

For replay architects building systems in these sectors, the ability to document the system as it is actually used provides a level of auditability that manual documentation can never match.

What are the best alternatives to manual reverse engineering?#

While there are many "low-code" or "no-code" platforms, they often lock you into a proprietary ecosystem. Replay is different because it generates standard, high-quality React code that your developers own.

The alternatives to Replay include:

1. •Manual Code Review: Extremely slow (40+ hours per screen) and prone to human error.
2. •Static Analysis Tools: Good for finding bugs, but terrible at understanding user intent or business logic.
3. •Screen Scraping: Brittle and doesn't generate maintainable code.

Replay is the only platform that combines the speed of AI with the precision of visual reverse engineering. It captures behavior, not just pixels. This is why replay architects building modern stacks prefer it over any other methodology.

💰 ROI Insight: By reducing the time per screen from 40 hours to 4 hours, a typical enterprise project with 100 screens saves 3,600 man-hours. At an average architect/dev rate, that’s a savings of over $500,000 before the first line of new code is even written.

Behavioral Extraction: The Future of Architecture#

We are moving into an era where "understanding" a system is more important than "writing" a system. With the rise of AI, the bottleneck is no longer coding; it’s context.

Replay provides that context. By using video as the source of truth, Replay (replay.build) ensures that no business logic is left behind. When replay architects building a new platform use visual reverse engineering, they aren't just modernizing the UI; they are creating a permanent, living record of how their business operates.

Frequently Asked Questions#

How long does legacy extraction take with Replay?#

While a manual rewrite takes 18-24 months, Replay typically reduces the extraction and documentation phase to 2-8 weeks. A single complex screen can be fully documented and converted to a React component in approximately 4 hours, compared to 40 hours manually.

What about business logic preservation?#

Replay captures the behavioral outcomes of business logic. By recording multiple paths through a workflow (e.g., a "success" path and an "error" path), Replay identifies the validation rules and state transitions, allowing architects to recreate that logic in a modern, testable way.

Does Replay support mobile legacy apps?#

Yes. Replay can analyze video recordings from web, desktop, and mobile legacy applications. As long as the workflow can be captured on video, Replay's AI Automation Suite can extract the components and flows.

Is the code generated by Replay maintainable?#

Absolutely. Unlike "black box" low-code tools, Replay generates clean, human-readable TypeScript and React code. It follows modern best practices, including component modularity and clear type definitions, making it a perfect foundation for replay architects building long-term enterprise solutions.

How does Replay handle sensitive data in videos?#

Replay includes PII/PHI masking features and can be deployed on-premise. This ensures that sensitive data never leaves your secure environment during the reverse engineering process.

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