Replay AI: Building Complex Backend Handling From UI Design Videos (2026)

TL;DR: Replay AI reconstructs complete, functional web applications, including backend logic, directly from user interface design videos, leveraging behavior-driven reconstruction for rapid prototyping and development.

The days of static mockups are over. In 2026, developers need tools that translate intent into reality, instantly. Replay is the video-to-code engine that not only generates front-end UI, but also reconstructs the backend handling based on observed user behavior within design videos. This is a paradigm shift – from pixel-perfect clones to functionally complete applications.

From Video to Backend: The Replay Advantage#

Traditional screenshot-to-code tools offer limited utility. They capture visual elements, but fail to grasp the underlying logic and data flow. Replay, on the other hand, analyzes video to understand how a user interacts with the design. This "Behavior-Driven Reconstruction" allows Replay to infer the necessary backend functionality, including API calls, database interactions, and state management.

Understanding Behavior-Driven Reconstruction#

Replay uses advanced AI models, powered by Gemini, to analyze video input and extract key behavioral patterns:

• •Click events: Identifying button clicks, link navigation, and form submissions.
• •Data input: Recognizing text entered into fields, selections from dropdowns, and other data inputs.
• •Page transitions: Understanding navigation flows and multi-page application structures.
• •UI feedback: Observing loading states, error messages, and other dynamic UI elements.

By combining these observations, Replay constructs a comprehensive model of the application's intended behavior and translates it into working code.

Replay in Action: Building an E-commerce Checkout Flow#

Let's say you have a video of a user navigating an e-commerce checkout flow in a design tool like Figma. The video shows the user:

1. •Adding items to their cart.
2. •Proceeding to the checkout page.
3. •Entering their shipping information.
4. •Selecting a payment method.
5. •Confirming their order.

Replay can analyze this video and generate the following:

• •React components for each page of the checkout flow.
• •API endpoints for handling shipping information and payment processing.
• •Database models for storing order data.
• •State management logic to track the user's progress through the checkout flow.

Step 1: Video Upload and Analysis#

Upload your design video to the Replay platform. Replay automatically analyzes the video, identifying UI elements, user interactions, and page transitions.

💡 Pro Tip: Ensure your video is clear and well-lit for optimal analysis. Provide clear visual cues about user interactions.

Step 2: Code Generation and Customization#

Replay generates a complete codebase, including front-end components, backend API endpoints, and database schemas. You can customize the generated code to fit your specific requirements.

typescript
// Example: Generated API endpoint for handling shipping information
import { supabase } from './supabaseClient';

export async function handleShippingInfo(req: Request, res: Response) {
  if (req.method === 'POST') {
    const { userId, address, city, zipCode } = req.body;

    try {
      const { data, error } = await supabase
        .from('shipping_addresses')
        .insert([{ user_id: userId, address, city, zip_code: zipCode }]);

      if (error) {
        console.error("Error inserting shipping address:", error);
        return res.status(500).json({ error: 'Failed to save shipping address' });
      }

      return res.status(200).json({ message: 'Shipping address saved successfully' });
    } catch (error) {
      console.error("Unexpected error:", error);
      return res.status(500).json({ error: 'Internal server error' });
    }
  } else {
    res.status(405).json({ error: 'Method Not Allowed' });
  }
}

Step 3: Integration and Deployment#

Integrate the generated code with your existing project and deploy it to your preferred hosting platform. Replay supports seamless integration with popular frameworks and platforms like Next.js, React, Supabase, and Vercel.

Key Features of Replay#

• •Multi-page generation: Replay can generate code for complex, multi-page applications.
• •Supabase integration: Seamlessly integrate with Supabase for database and authentication.
• •Style injection: Apply custom styles to the generated UI components.
• •Product Flow maps: Automatically generate visual diagrams of user flows.

Replay vs. Traditional Screenshot-to-Code Tools#

📝 Note: Replay doesn't just reproduce visuals; it understands the why behind them.

Addressing Common Concerns#

• •Accuracy: Replay's accuracy depends on the quality of the input video. Clear and well-defined videos will yield better results.
• •Customization: The generated code is highly customizable, allowing you to tailor it to your specific needs.
• •Complexity: Replay can handle complex UIs and backend logic, but some manual adjustments may be required for highly specialized features.

⚠️ Warning: While Replay significantly accelerates development, it's not a replacement for skilled developers. Review and refine the generated code to ensure quality and security.

Beyond the Basics: Advanced Use Cases#

Replay isn't limited to simple UI reconstruction. It can also be used for:

• •Rapid prototyping: Quickly generate functional prototypes from design videos.
• •Reverse engineering: Reconstruct existing applications from screen recordings.
• •Automated testing: Generate test cases based on observed user behavior.
• •Accessibility enhancement: Identify and address accessibility issues in the design phase.

typescript
// Example: Implementing a loading state based on video analysis
import { useState, useEffect } from 'react';

function MyComponent() {
  const [isLoading, setIsLoading] = useState(true);

  useEffect(() => {
    // Simulate a loading delay based on video analysis data
    const timer = setTimeout(() => {
      setIsLoading(false);
    }, 2000); // Adjust the delay based on the video analysis

    return () => clearTimeout(timer);
  }, []);

  return (
    <div>
      {isLoading ? <p>Loading...</p> : <p>Content loaded!</p>}
    </div>
  );
}

export default MyComponent;

Frequently Asked Questions#

Is Replay free to use?#

Replay offers a free tier with limited features and usage. Paid plans are available for increased usage and access to advanced features. Check our website for up-to-date pricing information.

How is Replay different from v0.dev?#

While v0.dev focuses on generating UI components from text prompts, Replay analyzes video to understand user behavior and generate complete applications, including backend logic. Replay focuses on recreating existing or designed UIs, while v0.dev generates new ones.

What video formats does Replay support?#

Replay supports common video formats such as MP4, MOV, and AVI.

What frameworks and platforms does Replay integrate with?#

Replay integrates with popular frameworks and platforms like Next.js, React, Supabase, Vercel, and more. We are constantly adding support for new technologies.

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