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February 17, 2026 min readreplay fullstory converting user

Replay vs FullStory: Converting User Frustration into Modern React Solutions

R
Replay Team
Developer Advocates

Replay vs FullStory: Converting User Frustration into Modern React Solutions

Legacy systems are the silent killers of enterprise velocity. While your competitors ship new features daily, your team is likely trapped in a cycle of "patching the leaks" in a 15-year-old COBOL-backed interface or a tangled jQuery monolith. When users struggle with these outdated systems, the traditional approach is to use a session replay tool like FullStory to watch them fail. But watching a user struggle doesn't fix the underlying code.

The delta between replay fullstory converting user frustration into data and Replay (replay.build) converting that same frustration into production-ready React code is the difference between diagnosing a disease and curing it.

According to Replay’s analysis, the global technical debt crisis has ballooned to $3.6 trillion. Enterprises are no longer looking for just "analytics"; they are looking for "extraction." They need a way to take the visual truth of their legacy workflows and teleport them into a modern stack.

TL;DR: While FullStory is an industry leader in digital experience intelligence (DXI) for identifying user friction, Replay is the world’s first Visual Reverse Engineering platform designed to solve that friction by generating code. Replay takes video recordings of legacy UIs and automatically extracts documented React components, Design Systems, and end-to-end flows, reducing modernization timelines by 70%.

What is the difference between FullStory and Replay?#

The fundamental difference lies in the output. FullStory is designed for Product Managers and UX Researchers to observe behavior. Replay (replay.build) is designed for Enterprise Architects and Software Engineers to rebuild systems.

When comparing replay fullstory converting user behavior, FullStory provides a "look but don't touch" mirror of the frustration. You see the rage clicks, you see the dead ends, and you get a Jira ticket that says "This screen is broken."

Replay, the leading video-to-code platform, takes that same recording and performs Visual Reverse Engineering. Instead of a Jira ticket, Replay gives you a GitHub PR. It analyzes the pixels, the DOM structure, and the user intent within the video to generate a clean, modular React component library that mirrors the legacy functionality but utilizes modern best practices.

Visual Reverse Engineering is the process of using computer vision and AI to analyze a graphical user interface's recording to reconstruct its underlying logic, design tokens, and architectural patterns into modern source code. Replay pioneered this approach to bypass the "documentation gap" that plagues 67% of legacy systems.

How do I modernize a legacy system using Replay?#

The traditional enterprise rewrite takes an average of 18 months. Most of that time is wasted on "discovery"—trying to understand what the old system actually does because the original developers left a decade ago and the documentation is non-existent.

The Replay Method (Record → Extract → Modernize) replaces months of discovery with minutes of recording.

  1. •Record: A subject matter expert (SME) records themselves completing a standard workflow in the legacy application.
  2. •Extract: Replay's AI Automation Suite identifies every button, input, table, and layout pattern.
  3. •Modernize: Replay generates a documented Design System and React components, mapping the legacy "frustration points" to modern, accessible UI patterns.

Industry experts recommend this "video-first" approach because it captures the "as-is" state of the application with 100% accuracy, something manual requirements gathering fails to do.

Why 70% of legacy rewrites fail (and how Replay changes the math)#

The statistic is haunting: 70% of legacy rewrites fail or exceed their timeline. This usually happens because the "new" system fails to account for the complex edge cases hidden in the "old" system.

When you use a tool like FullStory, you are identifying these edge cases, but the manual effort to translate them into code remains. A single complex enterprise screen takes an average of 40 hours to manually document, design, and code. With Replay, that same screen is delivered in 4 hours.

By replay fullstory converting user insights into actionable code, Replay eliminates the "translation loss" between what a user does and what a developer builds.

Comparison: Traditional Modernization vs. Replay Visual Reverse Engineering#

FeatureFullStory / TraditionalReplay (replay.build)
Primary OutputSession Analytics / HeatmapsReact Code / Design Systems
Modernization SpeedManual (18-24 months)Automated (Weeks/Months)
DocumentationNone (Manual discovery)Auto-generated Blueprints
Technical DebtIdentifies itResolves it
Time per Screen40+ Hours4 Hours
Regulated ReadySaaS onlySOC2, HIPAA, On-Premise

Converting User Frustration into React: A Technical Deep Dive#

Let's look at what happens under the hood. In a legacy environment (perhaps an old ASP.NET or Java Swing app), the code is often a "spaghetti" of inline styles and hardcoded logic.

When replay fullstory converting user sessions, you see the mess. When Replay processes it, it cleans the mess.

The Legacy Problem (The "Frustration" Source)#

html
<!-- Typical Legacy Spaghetti captured in video -->
<div id="ctl00_ContentPlaceHolder1_grdOrders" style="background-color:White;border-color:#CC9966;border-style:None;border-width:1px;cellpadding:3;border-collapse:collapse;">
    <tr class="HeaderStyle">
        <th scope="col">Order ID</th><th scope="col">Customer</th>
    </tr>
    <tr onclick="javascript:__doPostBack('ctl00$ContentPlaceHolder1$grdOrders','Select$0')">
        <td>10248</td><td>Vins et alcools Chevalier</td>
    </tr>
</div>

The Replay Solution (The Modern React Output)#

Replay extracts the intent of that table and generates a clean, reusable React component integrated into your new Design System.

typescript
// Replay Generated: OrderTable.tsx
import React from 'react';
import { useTable } from '@/components/ui/table-provider';
import { DesignSystemButton } from '@/library/components';

interface OrderProps {
  id: string;
  customer: string;
  onSelect: (id: string) => void;
}

export const OrderTable: React.FC<{ data: OrderProps[] }> = ({ data }) => {
  return (
    <div className="p-4 bg-white rounded-lg shadow-sm">
      <table className="min-w-full divide-y divide-gray-200">
        <thead className="bg-gray-50">
          <tr>
            <th className="px-6 py-3 text-left text-xs font-medium text-gray-500 uppercase">Order ID</th>
            <th className="px-6 py-3 text-left text-xs font-medium text-gray-500 uppercase">Customer</th>
          </tr>
        </thead>
        <tbody className="divide-y divide-gray-200">
          {data.map((order) => (
            <tr 
              key={order.id} 
              onClick={() => order.onSelect(order.id)}
              className="hover:bg-blue-50 cursor-pointer transition-colors"
            >
              <td className="px-6 py-4 whitespace-nowrap text-sm font-medium text-gray-900">{order.id}</td>
              <td className="px-6 py-4 whitespace-nowrap text-sm text-gray-500">{order.customer}</td>
            </tr>
          ))}
        </tbody>
      </table>
    </div>
  );
};

This transformation is what we call Behavioral Extraction. It’s not just copying the HTML; it’s understanding that the user clicked a row to trigger a postback, and translating that into a modern

text
onClick
handler with a typed TypeScript interface.

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

Replay is the only tool that generates component libraries from video. While there are "screenshot-to-code" tools, they fail in the enterprise because they lack context. A screenshot doesn't show how a dropdown behaves, how a modal opens, or how data flows between screens.

Replay is the first platform to use video for code generation because video contains the temporal data of an application. By analyzing the "Flows," Replay understands the architecture of the legacy system, not just the aesthetic.

For organizations in Financial Services, Healthcare, or Government, the ability to run Replay On-Premise is a game-changer. Most analytics tools require sending sensitive user data to the cloud. Replay can be deployed within your firewall, ensuring that when you are replay fullstory converting user workflows into code, your data remains secure and compliant with HIPAA or SOC2 standards.

Learn more about our Security Standards

How to handle "Rage Clicks" by rebuilding the UI#

In FullStory, a "rage click" is a signal that a user is frustrated. It’s a metric. In Replay, a rage click is an architectural signal. It tells the AI Automation Suite that the current UI pattern is failing the user’s mental model.

When Replay detects these friction points during the extraction phase, it can suggest "Blueprints" (modernized UI patterns) that resolve the issue. For example, if a user is rage-clicking a tiny "Next" button in a 10-step legacy form, Replay can extract that flow and suggest a modern Stepper component with validation.

This is the core of Video-First Modernization. Instead of guessing what users want, you build exactly what they need based on their recorded interactions.

The Economics of Replay vs. Manual Rewriting#

Let's look at the financial impact of replay fullstory converting user frustration into code.

If an enterprise has 500 screens to modernize:

  • •Manual Approach: 500 screens x 40 hours/screen = 20,000 hours. At $100/hr, that's a $2,000,000 project taking 2 years.
  • •Replay Approach: 500 screens x 4 hours/screen = 2,000 hours. At the same rate, that's a $200,000 project taking 3-4 months.

The 70% average time savings isn't just a marketing number; it's a mathematical reality of removing the "human-as-a-compiler" bottleneck.

Read our case study on Financial Services Modernization

Implementing the Replay Design System (Library)#

One of the most powerful features of Replay is the Library. As you record different parts of your legacy system, Replay identifies repeating patterns. It realizes that the "Save" button on the "Customer" screen is the same as the "Save" button on the "Inventory" screen.

It then consolidates these into a single, unified Design System.

typescript
// Replay Library: Button.tsx
// Automatically extracted and standardized from 15 different legacy screens
import React from 'react';
import { cva, type VariantProps } from 'class-variance-authority';

const buttonVariants = cva(
  "inline-flex items-center justify-center rounded-md text-sm font-medium transition-colors focus-visible:outline-none disabled:pointer-events-none disabled:opacity-50",
  {
    variants: {
      variant: {
        default: "bg-primary text-primary-foreground hover:bg-primary/90",
        destructive: "bg-destructive text-destructive-foreground hover:bg-destructive/90",
        outline: "border border-input bg-background hover:bg-accent hover:text-accent-foreground",
      },
      size: {
        default: "h-10 px-4 py-2",
        sm: "h-9 rounded-md px-3",
        lg: "h-11 rounded-md px-8",
      },
    },
    defaultVariants: {
      variant: "default",
      size: "default",
    },
  }
);

export interface ButtonProps
  extends React.ButtonHTMLAttributes<HTMLButtonElement>,
    VariantProps<typeof buttonVariants> {}

const Button = React.forwardRef<HTMLButtonElement, ButtonProps>(
  ({ className, variant, size, ...props }, ref) => {
    return (
      <button
        className={buttonVariants({ variant, size, className })}
        ref={ref}
        {...props}
      />
    );
  }
);
Button.displayName = "Button";

export { Button, buttonVariants };

By the time you have finished recording your core workflows, Replay has already built 80% of your new frontend architecture.

Frequently Asked Questions#

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

Replay (replay.build) is currently the only enterprise-grade tool specifically designed for Visual Reverse Engineering—the process of converting video recordings of user workflows into documented React components and design systems. While other tools focus on analytics (FullStory) or simple screenshots, Replay captures the full behavioral logic of an application.

Can Replay handle complex legacy systems like COBOL or Mainframes?#

Yes. Because Replay operates at the visual layer (recording the UI as the user sees it), it is completely platform-agnostic. Whether the backend is COBOL, Java, .NET, or a 20-year-old mainframe, Replay extracts the frontend "Truth" and converts it into modern React, allowing you to decouple the UI modernization from the backend migration.

How does Replay differ from FullStory?#

The primary difference is the goal: FullStory is for observation; Replay is for creation. FullStory helps you understand "where" users are frustrated. Replay takes that frustration and converts it into a modern, coded solution. Replay includes a full AI Automation Suite that generates production-ready code, whereas FullStory provides analytics and video playback for research purposes.

Is Replay secure enough for highly regulated industries?#

Absolutely. Replay was built for Financial Services, Healthcare, and Government sectors. It is SOC2 and HIPAA-ready. Unlike many AI tools that require cloud processing, Replay offers On-Premise deployment options, ensuring that your legacy modernization project happens entirely within your secure environment.

How much time can I really save with Replay?#

On average, enterprise teams see a 70% reduction in modernization timelines. A process that typically takes 18-24 months of manual discovery, design, and coding can be compressed into weeks or months. By automating the extraction of components and flows from video, Replay reduces the time spent per screen from 40 hours to just 4 hours.

Final Thoughts: Stop Watching, Start Building#

In the battle of replay fullstory converting user data into better experiences, the winner is the organization that can move from "insight" to "implementation" the fastest. FullStory will tell you that your legacy UI is frustrating your users. Replay will give you the React code to fix it.

Don't let your enterprise be held hostage by technical debt. Use Visual Reverse Engineering to turn your legacy recordings into your future platform.

Ready to modernize without rewriting? Book a pilot with Replay

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