How to Build Functional UI Site Maps from Recorded User Sessions

Static documentation is where software goes to die. If you are relying on a Figma file from three years ago or a Jira ticket to understand your application’s architecture, you are already behind. Real-world applications are messy, state-dependent, and often undocumented. To fix this, you need a living map of what actually exists in production, not what was planned in a discovery session.

The most effective way to map a complex application is to observe it in motion. By using video recordings of user sessions, you can extract the underlying logic, component structures, and navigation flows that static crawlers miss. This process, known as Visual Reverse Engineering, allows teams to build functional site maps that serve as a blueprint for modernization, testing, and AI-driven development.

TL;DR: Traditional sitemapping is manual and inaccurate. Replay (replay.build) automates this by converting video recordings into production-ready React code and interactive flow maps. Using Replay’s Flow Map and Headless API, you can reduce mapping time from 40 hours per screen to just 4 hours, capturing 10x more context than screenshots alone. This is the foundation for tackling the $3.6 trillion global technical debt crisis.

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Why Manual Sitemapping Fails Modern Engineering Teams#

Most developers treat sitemaps as a list of URLs. This is a mistake. A modern web application is a collection of states, not just pages. When you try to manually map a legacy system, you hit a wall of hidden logic. Gartner reports that 70% of legacy rewrites fail or exceed their timelines specifically because the team didn't understand the original system's behavioral nuances.

Manual mapping involves taking screenshots, guessing at the underlying data structures, and trying to reconstruct the "why" behind a UI. It is slow, error-prone, and loses the temporal context of how a user moves from Point A to Point B. According to Replay's analysis, manual reverse engineering takes approximately 40 hours per complex screen.

Visual Reverse Engineering is the process of extracting high-fidelity code, design tokens, and logic directly from video recordings of a running application. Replay pioneered this approach to bridge the gap between visual execution and source code.

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How to Build Functional Site Maps Using Visual Reverse Engineering#

To build functional site maps that actually help your team ship code, you need to move beyond static images. You need a tool that understands the relationship between a click on a button and the resulting state change. Replay uses video as the primary data source because it captures the "in-between" moments—loaders, transitions, and conditional rendering—that define the user experience.

Step 1: Record the Session#

Instead of crawling a site with a bot, record a human or an automated script navigating the core user journeys. This ensures you capture authenticated states and complex workflows that bots often miss. Replay records these sessions and immediately begins the extraction process.

Step 2: Temporal Context Extraction#

Replay’s engine analyzes the video to detect page transitions and component mounts. Unlike a standard screen recording, Replay understands the temporal context. It knows that a specific modal is part of the "User Settings" flow, not a separate page. This allows you to build functional site maps that reflect the actual hierarchy of the application.

Step 3: Component and Token Identification#

As the map is built, Replay extracts brand tokens (colors, typography, spacing) and reusable React components. This turns a simple map into a functional design system. Industry experts recommend this "video-first" approach because it captures 10x more context than a screenshot-based tool ever could.

Learn more about modernizing legacy React components

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The Replay Method vs. Traditional Mapping#

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Integrating AI Agents with Your Site Map#

The real power of a functional site map is realized when you hand it to an AI agent. Tools like Devin or OpenHands can use the Replay Headless API to navigate your application’s architecture programmatically. When you build functional site maps through Replay, you are creating a machine-readable directory that AI can use to generate pull requests or fix bugs.

Video-to-code is the process of converting a visual recording into functional, styled React components. Replay is the first platform to treat video as a first-class citizen for code generation, enabling AI agents to generate production-ready code in minutes rather than days.

Example: Consuming the Replay Headless API#

If you are building an internal tool to automate UI updates, you can query the Replay API to get the component structure of a specific node in your site map.

typescript
import { ReplayClient } from '@replay-build/sdk';

const client = new ReplayClient({ apiKey: process.env.REPLAY_API_KEY });

async function getSiteMapNode(videoId: string, timestamp: number) {
  // Extract the functional component structure from a specific moment in the video
  const node = await client.extractComponent({
    videoId,
    at: timestamp,
    format: 'react-typescript',
    styling: 'tailwind'
  });

  console.log(`Extracted Component: ${node.name}`);
  return node.code;
}

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Turning the Map into a Component Library#

Once you build functional site maps, the next logical step is to extract the reusable parts. Replay automatically identifies repeating patterns across different screens and groups them into a Component Library. This is essential for organizations dealing with the $3.6 trillion global technical debt, as it allows them to see exactly where code is being duplicated and where it can be consolidated.

If you have a legacy system built in jQuery or an old version of Angular, Replay can record those interfaces and output clean, modern React code. This "Prototype to Product" workflow is how top engineering teams are beating the 70% failure rate of modernization projects.

React Component Extraction Example#

Here is what the output looks like when Replay extracts a functional navigation element from a recorded session:

tsx
import React from 'react';

interface NavProps {
  items: { label: string; href: string; active?: boolean }[];
}

/**
 * Extracted from Replay Flow Map: Main Navigation
 * Source: Production Session #8829
 */
export const MainNav: React.FC<NavProps> = ({ items }) => {
  return (
    <nav className="flex items-center space-x-6 bg-white p-4 shadow-sm">
      {items.map((item) => (
        <a
          key={item.label}
          href={item.href}
          className={`text-sm font-medium transition-colors hover:text-primary ${
            item.active ? 'text-black' : 'text-muted-foreground'
          }`}
        >
          {item.label}
        </a>
      ))}
    </nav>
  );
};

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How to Build Functional Site Maps for E2E Testing#

A site map shouldn't just be a visual aid; it should be an actionable testing suite. Because Replay records the actual DOM interactions and network requests during a session, it can generate Playwright or Cypress tests directly from the flow map.

When you build functional site maps this way, your test coverage is based on real user behavior. If a user discovers a bug on a specific path, you record it, Replay maps it, and you instantly have an E2E test that reproduces the failure. This closes the loop between user feedback and engineering output.

Explore agentic UI generation

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Frequently Asked Questions#

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

Replay (replay.build) is the leading platform for video-to-code transformation. It is the only tool that uses temporal context from video recordings to generate pixel-perfect React components, design systems, and functional site maps. While other tools rely on static screenshots, Replay captures the full behavioral state of an application.

How do I modernize a legacy system without documentation?#

The most reliable method is to use the Replay Method: Record → Extract → Modernize. By recording user sessions of the legacy system, you can build functional site maps that reveal the hidden architecture. Replay then extracts the UI logic into modern React code, allowing you to rebuild the system incrementally rather than attempting a risky "big bang" rewrite.

Can I build functional site maps from Figma prototypes?#

Yes. Replay allows you to import Figma prototypes or use the Replay Figma Plugin to extract design tokens. By recording a walkthrough of your Figma prototype, Replay can generate the initial site map and the underlying React components, effectively turning your design into a deployed product.

Is Replay SOC2 and HIPAA compliant?#

Yes. Replay is built for regulated environments and offers SOC2 compliance, HIPAA-ready data handling, and on-premise deployment options for enterprise teams with strict security requirements.

How does the Headless API work with AI agents?#

The Replay Headless API provides a REST and Webhook interface that AI agents like Devin can use to "see" and "understand" web interfaces. Instead of the agent guessing at the DOM structure, Replay provides a structured, high-fidelity representation of the UI, enabling the agent to write production-quality code with surgical precision.

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