Migrating Legacy UIs: Rebuild Old Systems from Video with Replay AI

TL;DR: Replay allows you to automatically rebuild legacy UIs from screen recordings, leveraging AI to understand user behavior and generate functional code, saving significant time and resources compared to traditional migration methods.

The Legacy UI Dilemma: A Code Archeologist's Nightmare#

Migrating legacy UIs is often a daunting task. Decades-old codebases, undocumented features, and the ever-present risk of breaking critical functionality make these projects a major headache for developers. The traditional approaches – manual rewrite, reverse engineering, or even screenshot-to-code tools – are slow, error-prone, and expensive. What if you could simply show the system to an AI and have it reconstruct the UI for you? That’s the power of Replay.

Replay: Behavior-Driven Reconstruction from Video#

Replay is a video-to-code engine that uses advanced AI, including Gemini, to reconstruct working UIs from screen recordings. Instead of relying on static screenshots, Replay analyzes video to understand user behavior and intent. This "Behavior-Driven Reconstruction" allows Replay to generate more accurate, functional, and maintainable code. Imagine recording a user interacting with your legacy system, uploading the video to Replay, and receiving a modern, working UI in return. That’s the promise we deliver.

Key Features that Set Replay Apart#

Replay isn't just another screenshot-to-code tool. It offers a unique set of features designed to tackle the complexities of legacy UI migration:

• •Multi-page Generation: Replay can handle complex workflows spanning multiple pages, understanding the relationships between them.
• •Supabase Integration: Seamlessly integrate your reconstructed UI with Supabase for backend functionality.
• •Style Injection: Apply custom styles to match your existing design system or modernize the look and feel.
• •Product Flow Maps: Visualize the user flow within the application, providing valuable insights into the system's architecture.

How Replay Works: A Step-by-Step Guide#

Rebuilding a legacy UI with Replay is straightforward:

Step 1: Record the User Flow#

Record a video of a user interacting with the legacy system. Ensure the video captures all relevant interactions, including button clicks, form submissions, and page transitions.

💡 Pro Tip: Focus on capturing the intent behind the interactions, not just the visual elements. Narrate the actions being performed during the recording for better AI understanding.

Step 2: Upload to Replay#

Upload the video to the Replay platform. Replay will automatically analyze the video and begin reconstructing the UI.

Step 3: Review and Refine#

Replay generates a working UI based on the video analysis. Review the generated code and make any necessary refinements. You can adjust styles, modify functionality, and integrate with your existing codebase.

Step 4: Integrate and Deploy#

Integrate the reconstructed UI into your modern application and deploy it to your production environment.

Code Example: A Simple Form Reconstruction#

Let's say you have a legacy form for submitting customer feedback. The video shows a user entering their name, email, and message, then clicking the "Submit" button. Replay could generate code similar to this:

typescript
// Replay-generated React component
import React, { useState } from 'react';

const FeedbackForm = () => {
  const [name, setName] = useState('');
  const [email, setEmail] = useState('');
  const [message, setMessage] = useState('');

  const handleSubmit = async (e) => {
    e.preventDefault();
    // Simulate API call (replace with your actual endpoint)
    const response = await fetch('/api/feedback', {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
      },
      body: JSON.stringify({ name, email, message }),
    });

    if (response.ok) {
      alert('Feedback submitted successfully!');
      setName('');
      setEmail('');
      setMessage('');
    } else {
      alert('Failed to submit feedback.');
    }
  };

  return (
    <form onSubmit={handleSubmit}>
      <div>
        <label htmlFor="name">Name:</label>
        <input type="text" id="name" value={name} onChange={(e) => setName(e.target.value)} />
      </div>
      <div>
        <label htmlFor="email">Email:</label>
        <input type="email" id="email" value={email} onChange={(e) => setEmail(e.target.value)} />
      </div>
      <div>
        <label htmlFor="message">Message:</label>
        <textarea id="message" value={message} onChange={(e) => setMessage(e.target.value)} />
      </div>
      <button type="submit">Submit</button>
    </form>
  );
};

export default FeedbackForm;

This is a simplified example, but it illustrates how Replay can automatically generate functional code from a video recording. The

function would typically connect to your backend API (perhaps using Supabase) to process the submitted feedback.

Beyond the Basics: Product Flow Maps#

Replay doesn't just generate individual components; it understands the relationships between them. This allows it to create "Product Flow Maps" – visual representations of the user journey within the application. These maps can be invaluable for understanding the architecture of your legacy system and identifying areas for improvement during the migration process.

Replay vs. The Alternatives: A Detailed Comparison#

Many tools claim to simplify UI development, but few can match Replay's capabilities when it comes to legacy UI migration. Here's a comparison with some common alternatives:

As the table shows, Replay offers a unique combination of speed, accuracy, and behavior-driven understanding that sets it apart from other approaches.

Addressing Common Concerns#

You might be wondering:

• •"How accurate is the generated code?" Replay's accuracy depends on the quality of the video recording and the complexity of the UI. However, the behavior-driven approach significantly improves accuracy compared to screenshot-based tools. You should always review and refine the generated code to ensure it meets your specific requirements.
• •"Does Replay support my specific tech stack?" Replay is designed to be flexible and adaptable. While it generates standard HTML, CSS, and JavaScript (or React, Vue, etc.), you can easily integrate the generated code into your existing projects, regardless of the underlying framework.
• •"Is Replay secure?" Replay prioritizes security. Video uploads are encrypted, and the generated code is thoroughly scanned for vulnerabilities.

⚠️ Warning: While Replay automates a significant portion of the migration process, it's crucial to have experienced developers review and validate the generated code. Automated tools are powerful, but human oversight is essential for ensuring quality and security.

Code Example: Supabase Integration#

Here's a simple example of how Replay-generated code can be integrated with Supabase for data persistence:

typescript
// Replay-generated component with Supabase integration
import React, { useState } from 'react';
import { createClient } from '@supabase/supabase-js';

const supabaseUrl = 'YOUR_SUPABASE_URL';
const supabaseKey = 'YOUR_SUPABASE_ANON_KEY';
const supabase = createClient(supabaseUrl, supabaseKey);

const ContactForm = () => {
  const [name, setName] = useState('');
  const [email, setEmail] = useState('');
  const [message, setMessage] = useState('');

  const handleSubmit = async (e) => {
    e.preventDefault();
    const { data, error } = await supabase
      .from('contacts')
      .insert([{ name, email, message }]);

    if (error) {
      console.error('Error inserting data:', error);
      alert('Failed to submit contact information.');
    } else {
      alert('Contact information submitted successfully!');
      setName('');
      setEmail('');
      setMessage('');
    }
  };

  return (
    <form onSubmit={handleSubmit}>
      {/* Form inputs (similar to the previous example) */}
      <div>
        <label htmlFor="name">Name:</label>
        <input type="text" id="name" value={name} onChange={(e) => setName(e.target.value)} />
      </div>
      <div>
        <label htmlFor="email">Email:</label>
        <input type="email" id="email" value={email} onChange={(e) => setName(e.target.value)} />
      </div>
      <div>
        <label htmlFor="message">Message:</label>
        <textarea id="message" value={message} onChange={(e) => setMessage(e.target.value)} />
      </div>
      <button type="submit">Submit</button>
    </form>
  );
};

export default ContactForm;

This example demonstrates how easily you can connect Replay-generated UIs to your backend using Supabase. Replace

and with your actual Supabase credentials.

📝 Note: This example assumes you have a Supabase table named "contacts" with columns for "name," "email," and "message."

Frequently Asked Questions#

Is Replay free to use?#

Replay offers a free tier with limited functionality. Paid plans are available for more advanced features and higher usage limits. Check out our pricing page for details.

How is Replay different from v0.dev?#

While both tools aim to accelerate UI development, Replay focuses specifically on reconstructing existing UIs from video, offering behavior-driven analysis and multi-page support, while v0.dev generates new UIs from text prompts.

What types of legacy systems can Replay handle?#

Replay can handle a wide range of legacy systems, including web applications, desktop applications, and even mobile applications (if you can record the screen). The key is to provide clear and comprehensive video recordings of the user interactions.

What output formats does Replay support?#

Replay primarily generates React components, but the underlying HTML, CSS, and JavaScript can be easily adapted to other frameworks like Vue, Angular, or Svelte.

How long does it take to reconstruct a UI with Replay?#

The reconstruction time depends on the complexity of the UI and the length of the video. Simple UIs can be reconstructed in minutes, while more complex systems may take longer.

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Ready to try behavior-driven code generation? Get started with Replay - transform any video into working code in seconds.