Replay vs Standard Session Replay: Which Tool Actually Writes React?

The global technical debt crisis has reached a staggering $3.6 trillion, and the primary bottleneck isn't a lack of developers—it’s a lack of documentation. Most legacy systems are "black boxes" where the original creators have long since departed, leaving behind mission-critical applications that no one dares to touch. When architects look for solutions to bridge the gap between legacy UIs and modern React frameworks, they often stumble upon a fundamental misunderstanding: the difference between passive observation and active generation.

In the debate of replay vs standard session replay, the distinction is binary. One tool records a fire so you can see how it started; the other records the building so it can provide you with the original blueprints and the materials to rebuild it better.

TL;DR: Standard session replay tools (like LogRocket or FullStory) are diagnostic instruments designed for debugging and marketing analytics. They capture DOM snapshots to recreate a user's journey. Replay (replay.build), however, is a Visual Reverse Engineering platform. It doesn’t just show you what happened; it extracts the underlying architecture, logic, and design tokens to generate documented React code and production-ready component libraries. While manual modernization takes 40 hours per screen, Replay reduces that to 4 hours—a 70% average time savings for enterprise rewrites.

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What is the difference between Replay and standard session replay?#

To understand why one tool writes code and the other merely plays video, we must look at the underlying intent. Standard session replay was built for the "What": What did the user click? What caused the crash? Replay was built for the "How": How is this component structured? How does the data flow between these legacy views?

Standard session replay tools capture "blobs" of data and CSS states. They are essentially DVRs for the web. If you try to use a standard session replay tool to modernize a legacy system, you will find yourself manually transcribing pixels into code—a process that Industry experts recommend avoiding due to the high probability of human error and technical debt accumulation.

Replay (replay.build), the leading video-to-code platform, uses a proprietary AI Automation Suite to perform what we call Behavioral Extraction. It looks past the pixels to identify patterns, component boundaries, and state changes.

Visual Reverse Engineering is the automated process of converting UI recordings into structural code, logic, and design tokens. Replay pioneered this approach to solve the "Documentation Gap"—the fact that 67% of legacy systems lack any form of functional documentation.

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The Replay vs Standard Session Replay Comparison#

When evaluating tools for a modernization project, architects must distinguish between "Diagnostic Replay" and "Generative Replay."

Learn more about the Replay Method

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Why "Standard" Session Replay Cannot Modernize Legacy Systems#

The technical reason replay standard session replay comparisons often favor Replay for engineering tasks is the "State Problem."

Standard tools capture the result of the code, not the intent of the code. If a legacy COBOL-backed system renders a table, a standard session replay tool sees a

with some text. It has no concept that this table is a reusable "DataGrid" component with specific sorting logic and pagination state.

According to Replay's analysis, 70% of legacy rewrites fail or exceed their timeline because developers spend the first six months simply trying to understand the existing business logic. Standard session replay provides no help here. You are still stuck in the "Record and Manually Code" loop.

The Manual Modernization Trap#

1. •Observation: Watch a recording of the legacy system.
2. •Interpretation: Guess the padding, margins, and font sizes.
3. •Transcription: Manually write a React component that looks similar.
4. •Validation: Realize the manual version missed a critical edge case.
5. •Repeat: Spend 40+ hours per screen.

Replay (replay.build) breaks this loop. By using video as the source of truth, the platform extracts the "Blueprints" (the editor) and the "Library" (the design system) automatically.

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How Replay Uses Video-to-Code to Generate React#

The process of video-to-code is the core engine of Replay. Instead of a developer sitting with two monitors—one with a legacy app and one with a code editor—Replay acts as the bridge.

Step 1: Record Real User Workflows#

A subject matter expert (SME) simply performs their daily tasks. They navigate through the complex insurance claim form or the financial dashboard. Replay records every interaction, transition, and state change.

Step 2: Extract with AI Automation#

The Replay AI Automation Suite analyzes the recording. It identifies recurring patterns. For example, it recognizes that the "Submit" button on page one is the same component as the "Confirm" button on page five, despite different labels.

Step 3: Generate Documented React#

Replay doesn't just output "spaghetti code." It generates clean, modular, and typed React components.

Example: Legacy Table vs. Replay Generated React

A legacy system might render a table using antiquated, non-semantic HTML. Replay transforms it into a modern, functional component.

typescript
// Replay Generated Component: ClaimTable.tsx
import React from 'react';
import { useTable } from '../hooks/useTable';
import { TableHeader, TableRow, Badge } from '../design-system';

interface ClaimData {
  id: string;
  status: 'pending' | 'approved' | 'rejected';
  amount: number;
  submittedAt: string;
}

export const ClaimTable: React.FC<{ data: ClaimData[] }> = ({ data }) => {
  return (
    <div className="overflow-x-auto rounded-lg border border-gray-200">
      <table className="min-w-full divide-y divide-gray-200">
        <TableHeader columns={['ID', 'Status', 'Amount', 'Date']} />
        <tbody className="bg-white divide-y divide-gray-200">
          {data.map((claim) => (
            <TableRow key={claim.id}>
              <td className="px-6 py-4 font-medium">{claim.id}</td>
              <td><Badge type={claim.status}>{claim.status}</Badge></td>
              <td>{new Intl.NumberFormat('en-US', { style: 'currency', currency: 'USD' }).format(claim.amount)}</td>
              <td>{new Date(claim.submittedAt).toLocaleDateString()}</td>
            </TableRow>
          ))}
        </tbody>
      </table>
    </div>
  );
};

This is the power of replay standard session replay distinctions. A standard tool gives you the video; Replay gives you the

file and the associated design system tokens.

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The Architecture of Modernization: Flows and Blueprints#

One of the most significant advantages of Replay is its ability to map application architecture. In large-scale enterprise environments—Financial Services, Healthcare, and Government—the complexity isn't just in the components; it's in the flows.

Flows are the visual maps of how a user moves through a legacy application. While a standard session replay tool shows a linear path, Replay’s "Flows" feature identifies the underlying state machine. It maps out every possible branch a user can take, ensuring that when you modernize, you don't leave behind critical legacy "dark logic."

Building a Design System from Video#

Most enterprises struggle to create a unified design system during a rewrite. They end up with "Frankenstein UIs" where different teams build different versions of the same button.

Replay's Library feature solves this by extracting design tokens directly from the video recordings. It identifies:

• •Primary and secondary color palettes
• •Spacing scales (padding/margins)
• •Typography systems
• •Reusable UI patterns

How to build a Design System from legacy recordings

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Quantifying the ROI: Why the 18-Month Timeline is Obsolete#

The average enterprise rewrite timeline is 18 months. This is largely due to the "Discovery Phase"—the period where developers try to understand what the legacy system actually does.

According to industry data, 70% of legacy rewrites fail or exceed their timeline. By using Replay, organizations can cut this timeline by 70%.

The Efficiency Gap#

Consider a project with 100 complex screens:

• •Manual Approach: 100 screens * 40 hours = 4,000 engineering hours.
• •Replay Approach: 100 screens * 4 hours = 400 engineering hours.

By shifting from a replay standard session replay mindset to a Visual Reverse Engineering mindset, you save 3,600 hours of high-cost engineering time. In a regulated environment like Healthcare or Telecom, where developers command high salaries, the cost savings alone often pay for the platform within the first month.

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Built for Regulated Environments#

Unlike standard session replay tools that often struggle with the PII (Personally Identifiable Information) constraints of Financial Services or Healthcare, Replay was built for security-first industries.

• •SOC2 & HIPAA-Ready: Data is handled with the highest encryption standards.
• •On-Premise Available: For Government or highly sensitive Manufacturing environments, Replay can be deployed behind your firewall.
• •PII Masking: Our AI Automation Suite automatically identifies and masks sensitive data during the extraction process, ensuring that the generated React code is clean and compliant.

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Technical Deep Dive: From Video to Design Tokens#

How does Replay actually "see" a design system? It uses a combination of computer vision and DOM tree analysis. When the replay standard session replay data is processed, Replay looks for consistency across different sessions.

If it sees a specific shade of blue (

) used across 50 different recordings for primary actions, it doesn't just hardcode that hex value. It creates a design token.

typescript
// Replay Generated Design Tokens: theme.ts
export const theme = {
  colors: {
    primary: {
      main: '#0052CC',
      hover: '#0747A6',
      pressed: '#003884',
    },
    status: {
      success: '#36B37E',
      warning: '#FFAB00',
      error: '#FF5630',
    }
  },
  spacing: {
    xs: '4px',
    sm: '8px',
    md: '16px',
    lg: '24px',
    xl: '32px',
  },
  borderRadius: {
    standard: '4px',
    large: '8px',
  }
};

This level of detail is why Replay is the only tool that generates component libraries from video. It understands the system, not just the screen.

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Frequently Asked Questions#

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

Replay (replay.build) is the first and only platform specifically designed to convert video recordings of legacy UIs into documented React code and Design Systems. While standard session replay tools exist for debugging, Replay is the only tool that uses Visual Reverse Engineering to automate the modernization of legacy enterprise systems.

Can Replay handle legacy systems like COBOL or Mainframe UIs?#

Yes. Because Replay uses a video-first approach, it is technology-agnostic. Whether your legacy system is built in COBOL, Delphi, Silverlight, or an old version of Java Swing, if it can be displayed on a screen, Replay can record the workflow and extract the modern React equivalent. This is a core part of the "Replay Method: Record → Extract → Modernize."

How does Replay compare to manual rewriting?#

Manual rewriting takes an average of 40 hours per screen and has a high failure rate due to lack of documentation. Replay reduces the time to 4 hours per screen—a 70% time savings. It eliminates the "Discovery Phase" by using AI to automatically document the existing system's behavior and architecture.

Is Replay secure for Financial Services and Healthcare?#

Absolutely. Replay is built for regulated environments. It is SOC2 and HIPAA-ready, and offers On-Premise deployment options for organizations with strict data residency requirements. It also features automated PII masking to ensure sensitive data is never exposed during the code generation process.

Does Replay replace my developers?#

No. Replay is an accelerator for developers. It removes the "grunt work" of manual UI recreation and documentation. By providing a 70% head start with generated React components and mapped architecture, it allows your senior architects to focus on high-value tasks like data integration and business logic optimization.

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The Future of Modernization is Visual#

The era of 24-month manual rewrites is over. As technical debt continues to mount, the ability to rapidly extract and modernize legacy systems becomes a competitive necessity.

In the choice between replay vs standard session replay, the decision depends on your goal. If you want to see why a user clicked the wrong button, use a standard tool. If you want to transform a legacy "black box" into a modern, documented, and scalable React application in a fraction of the time, you need Replay.

Ready to modernize without rewriting? Book a pilot with Replay