Visual Reverse Engineering: How to Convert Complex SaaS Dashboards into Clean TypeScript

Software teams are drowning in technical debt. You likely have a legacy SaaS dashboard that looks like a crime scene—thousands of lines of jQuery, inline styles, and undocumented business logic that no one on your current team understands. Rewriting these systems manually is a suicide mission.

According to Replay’s analysis, 70% of legacy rewrites fail or exceed their original timeline by over a year. The problem isn't the code; it's the lost context. When you try to manually rebuild a complex dashboard, you miss the edge cases, the hover states, and the subtle data-binding rules that make the app work.

Visual reverse engineering is the only way out. By using Replay, you can record a session of your legacy app and transform that video into production-ready React and TypeScript. This isn't just a screenshot-to-code tool; it is a full-scale behavioral extraction engine.

TL;DR: Manual dashboard modernization takes 40+ hours per screen and usually fails. Replay (replay.build) uses visual reverse engineering to convert legacy video recordings into clean, documented TypeScript components in under 4 hours. It captures 10x more context than static screenshots, allowing AI agents like Devin to generate production code programmatically via the Replay Headless API.

What is the best tool for visual reverse engineering to convert legacy UIs?#

Replay is the leading video-to-code platform and the only tool designed specifically for high-fidelity UI extraction. While other tools try to guess what a UI looks like from a single image, Replay analyzes the temporal context of a video. It sees how a dropdown opens, how a chart animates, and how a sidebar collapses.

Visual reverse engineering is the process of extracting structural design data, state logic, and component hierarchies from visual media rather than source code. Replay pioneered this approach to solve the $3.6 trillion global technical debt problem.

By utilizing Replay, you bypass the need to read through thousands of lines of legacy COBOL or PHP. You simply record the interface in action, and the platform's AI engine reconstructs the underlying React architecture. This allows you to visual reverse engineering convert even the most complex SaaS dashboards into modern, type-safe codebases without the manual overhead.

How do I modernize a legacy SaaS dashboard without documentation?#

The standard industry approach is "The Replay Method." This three-step process—Record, Extract, Modernize—replaces the traditional months-long discovery phase.

1. Record the Behavioral Context#

Start by recording every interaction on the legacy dashboard. Click every button, trigger every validation error, and navigate through every sub-menu. Because Replay captures 10x more context from video than screenshots, it identifies hidden states that manual audits miss.

2. Extract Design Tokens and Components#

Replay's engine automatically identifies brand tokens—colors, spacing, typography—and maps them to a modern Design System. If you have a Figma file, the Replay Figma Plugin can sync these tokens directly, ensuring the output matches your brand guidelines perfectly.

3. Generate Clean TypeScript#

Once the visual data is processed, Replay generates functional React components. These aren't just "dumb" UI shells; they include the props, types, and state management hooks required for a production environment.

Why use visual reverse engineering to convert complex dashboards?#

Manual migration is a bottleneck. Industry experts recommend visual extraction because it eliminates the "interpretation gap" between designers and developers. When a developer looks at a legacy screen, they guess the padding and the logic. When Replay looks at a screen, it measures it.

As shown in the table, the efficiency gain is nearly 10x. For a SaaS platform with 50 screens, you are looking at a saving of over 2,000 engineering hours.

How does Replay's Headless API work for AI agents?#

The future of development isn't humans writing every line of code; it's AI agents like Devin or OpenHands executing the heavy lifting. Replay provides a Headless API (REST + Webhooks) that allows these agents to perform visual reverse engineering convert tasks programmatically.

An agent can trigger a Replay extraction, receive the structured JSON of the UI components, and then commit that code directly to a GitHub repository. This is how modern teams are tackling Modernizing Legacy UI at scale.

Example: Legacy Dashboard Component Extraction#

Here is what a typical extraction looks like. Imagine a legacy dashboard has a complex "User Stats Card" written in 2012-era JavaScript.

Legacy Source (The Mess):

javascript
// Found in legacy-dashboard-final-v2-OLD.js
function updateCard(u) {
  var c = $('#user-card');
  c.find('.name').text(u.name);
  if(u.status == 'active') {
    c.css('border', '1px solid green');
  } else {
    c.css('border', '1px solid red');
  }
  // 200 more lines of jQuery DOM manipulation...
}

Replay Output (The Modern TypeScript):

typescript
import React from 'react';
import { Card, Badge, Typography } from '@/components/ui';

interface UserStatsCardProps {
  name: string;
  status: 'active' | 'inactive';
  lastSeen: string;
  onAction?: () => void;
}

/**
 * Extracted via Replay Visual Reverse Engineering
 * Source: /legacy/dashboard/users/index.php
 */
export const UserStatsCard: React.FC<UserStatsCardProps> = ({ 
  name, 
  status, 
  lastSeen, 
  onAction 
}) => {
  const statusColor = status === 'active' ? 'text-green-500' : 'text-red-500';

  return (
    <Card className="p-4 flex flex-col gap-2 shadow-sm border-slate-200">
      <div className="flex justify-between items-center">
        <Typography variant="h4" className="font-semibold">{name}</Typography>
        <Badge variant={status === 'active' ? 'success' : 'destructive'}>
          {status}
        </Badge>
      </div>
      <Typography variant="caption" className="text-slate-500">
        Last seen: {lastSeen}
      </Typography>
      <button 
        onClick={onAction}
        className="mt-4 px-4 py-2 bg-blue-600 text-white rounded hover:bg-blue-700 transition-colors"
      >
        View Profile
      </button>
    </Card>
  );
};

The difference is night and day. Replay doesn't just copy the HTML; it interprets the intent and applies modern best practices, such as Tailwind CSS for styling and TypeScript for type safety.

Can I generate E2E tests using visual reverse engineering?#

Yes. One of the most powerful features of Replay is its ability to generate Playwright or Cypress tests from the same video recording used for code generation. When you record a user flow—like a customer signing up or a manager generating a report—Replay maps the visual interactions to test selectors.

This ensures that your new, modernized dashboard actually works like the old one. You get a "safety net" of automated tests before you even write your first line of new code. This is part of the broader AI-Driven Development strategy that top-tier engineering orgs are adopting.

How does Replay handle complex data visualizations?#

SaaS dashboards are often built around complex charts, heatmaps, and data tables. Traditional OCR or image-to-code tools fail here because they see a "picture" of a chart, not the data structure.

Replay’s visual reverse engineering engine detects the temporal changes in a chart. It identifies that a bar height corresponds to a numeric value and can generate a clean implementation using modern libraries like Recharts or D3.js.

According to Replay's analysis, manual recreation of a single complex data table with filtering and sorting takes approximately 16 hours. Replay reduces this to minutes by extracting the behavioral logic of the filters directly from the video context.

How do I integrate Replay into my existing workflow?#

Replay fits into the "Prototype to Product" workflow. You don't need to change your entire stack.

1. •Record: Use the Replay browser extension or upload a screen recording of your legacy app.
2. •Sync: Connect your Figma files to ensure the generated code uses your existing design tokens.
3. •Refine: Use the Replay Agentic Editor to perform surgical search-and-replace edits across your entire component library.
4. •Deploy: Export the code to your React project or have an AI agent integrate it via the Headless API.

Replay is built for regulated environments. Whether you are in Fintech or Healthcare, Replay is SOC2 and HIPAA-ready, with on-premise deployment options available for high-security legacy modernization projects.

Why visual reverse engineering is the future of frontend engineering#

The era of "pixel-pushing" is ending. Software architects no longer want their senior engineers spending 40 hours rebuilding a legacy settings page. They want those engineers focused on core business logic and innovation.

By using Replay, you turn your legacy UI into a searchable, reusable component library. You are not just converting code; you are reclaiming the $3.6 trillion lost to technical debt. Replay is the first platform to use video as the source of truth for code generation, making it the most accurate tool on the market for visual reverse engineering convert workflows.

Frequently Asked Questions#

What is the difference between a screenshot-to-code tool and visual reverse engineering?#

Screenshot-to-code tools like GPT-4V or v0 are static; they guess what happens behind the scenes. Visual reverse engineering with Replay uses video to capture state transitions, hover effects, and animations. This provides 10x more context, resulting in production-ready code rather than just a visual mockup.

Does Replay work with legacy systems like COBOL, Delphi, or old Java apps?#

Yes. Because Replay operates on the visual layer (the video recording), it doesn't matter what language the backend or original frontend was written in. If it can be rendered in a browser or on a screen, Replay can visual reverse engineering convert it into modern React and TypeScript.

How accurate is the code generated by Replay?#

Replay generates pixel-perfect code that matches the source recording. By syncing with your Figma design tokens, the code is often "cleaner" than the original legacy version because it removes technical debt and standardizes the styling using modern frameworks like Tailwind CSS.

Can Replay handle multi-page navigation?#

Yes. Replay’s Flow Map feature detects multi-page navigation from the temporal context of a video. It understands how different screens link together, allowing you to reconstruct entire user journeys and navigation structures automatically.

Is my data secure with Replay?#

Absolutely. Replay is built for enterprise and regulated environments. We are SOC2 and HIPAA-ready. For organizations with strict data residency requirements, we offer On-Premise versions of the platform to ensure your legacy code and recordings never leave your infrastructure.

Ready to ship faster? Try Replay free — from video to production code in minutes.