Replay AI for Reverse Engineering UI Code from Screen Recording Videos

TL;DR: Replay AI leverages video analysis and Gemini to reconstruct fully functional UI code from screen recordings, offering a superior alternative to screenshot-based code generation.

The "screenshot-to-code" revolution promised instant UI generation, but it's fundamentally flawed. Static images can't capture dynamic user behavior or the underlying logic driving the interface. What if you could reverse engineer working code, directly from a video of a user interacting with an existing UI? That's the power of Replay.

The Problem with Screenshots: A Static View of a Dynamic World#

Screenshot-to-code tools treat UI as a collection of pixels. They lack the context of user interactions, animations, and the flow between different states. This leads to brittle, incomplete code that requires significant manual tweaking. They are good for simple layouts, but break down quickly with complex interactions.

Consider a simple form with validation. A screenshot only shows the initial state, not the error messages, the successful submission, or the underlying validation logic. Replay, on the other hand, captures the entire interaction, allowing it to infer the intended behavior and generate more robust code.

Introducing Replay: Behavior-Driven Reconstruction#

Replay takes a fundamentally different approach: Behavior-Driven Reconstruction. We analyze video recordings of user interactions to understand not just what the UI looks like, but how it behaves. This allows Replay to generate code that is:

• •Functional: The generated UI actually works, not just looks like the original.
• •Maintainable: Replay infers the underlying logic, making the code easier to understand and modify.
• •Complete: Replay captures multi-page flows and dynamic interactions, generating complete applications.

Replay leverages Gemini's advanced video understanding capabilities to achieve this. We don't just see pixels; we see user intent.

Key Features that Set Replay Apart#

Multi-Page Generation#

Unlike screenshot tools limited to single screens, Replay tracks user navigation across multiple pages. This allows it to generate complete application flows, including routing and state management.

Supabase Integration#

Seamlessly integrate your generated code with Supabase, the open-source Firebase alternative. Replay can automatically generate data models and API calls based on the observed UI interactions.

Style Injection#

Replay analyzes the visual style of the original UI and injects it into the generated code. This ensures a pixel-perfect replica of the original design, while also providing flexibility to customize the styling later.

Product Flow Maps#

Replay generates visual flow maps of the user interactions captured in the video. This provides a clear overview of the application's logic and makes it easier to understand and modify the generated code.

Replay vs. Screenshot-to-Code: A Head-to-Head Comparison#

💡 Pro Tip: Replay is especially powerful for reverse engineering complex UIs with dynamic interactions, such as e-commerce checkouts or data dashboards.

Building a UI from a Video: A Step-by-Step Guide#

Let's walk through a simple example of using Replay to generate code from a video of a user interacting with a simple to-do list application.

Step 1: Upload the Video#

Upload the video recording of the user interacting with the to-do list application to the Replay platform.

Step 2: Replay Analyzes the Video#

Replay analyzes the video, identifying the UI elements, user interactions, and the underlying logic. This process takes just a few seconds.

Step 3: Generate the Code#

Replay generates the code for the to-do list application, including the UI components, event handlers, and data management logic. You can choose your preferred framework (React, Vue, etc.).

Step 4: Customize and Deploy#

Review the generated code, customize it as needed, and deploy it to your platform of choice.

📝 Note: Replay provides a visual editor that allows you to fine-tune the generated code and preview the UI in real-time.

Code Example: Generated React Component#

Here's an example of a React component generated by Replay:

typescript
// Generated by Replay AI
import React, { useState } from 'react';

interface Todo {
  id: number;
  text: string;
  completed: boolean;
}

const TodoList: React.FC = () => {
  const [todos, setTodos] = useState<Todo[]>([
    { id: 1, text: 'Learn Replay AI', completed: false },
    { id: 2, text: 'Build a cool app', completed: false },
  ]);

  const [newTodo, setNewTodo] = useState('');

  const handleInputChange = (event: React.ChangeEvent<HTMLInputElement>) => {
    setNewTodo(event.target.value);
  };

  const handleAddTodo = () => {
    if (newTodo.trim() !== '') {
      setTodos([...todos, { id: Date.now(), text: newTodo, completed: false }]);
      setNewTodo('');
    }
  };

  const handleCompleteTodo = (id: number) => {
    setTodos(
      todos.map((todo) =>
        todo.id === id ? { ...todo, completed: !todo.completed } : todo
      )
    );
  };

  return (
    <div>
      <h1>Todo List</h1>
      <input
        type="text"
        value={newTodo}
        onChange={handleInputChange}
        placeholder="Add new todo"
      />
      <button onClick={handleAddTodo}>Add</button>
      <ul>
        {todos.map((todo) => (
          <li key={todo.id}>
            <input
              type="checkbox"
              checked={todo.completed}
              onChange={() => handleCompleteTodo(todo.id)}
            />
            <span style={{ textDecoration: todo.completed ? 'line-through' : 'none' }}>
              {todo.text}
            </span>
          </li>
        ))}
      </ul>
    </div>
  );
};

export default TodoList;

This code is not just a static representation of the UI. It includes the state management, event handlers, and data manipulation logic necessary to make the to-do list functional.

Beyond Basic Code Generation: Unlocking New Possibilities#

Replay opens up a range of exciting possibilities:

• •Reverse Engineering Legacy Systems: Quickly generate code from videos of users interacting with legacy applications, making it easier to modernize and maintain them.
• •Prototyping and Iteration: Rapidly prototype new UI designs by recording user interactions and generating code automatically.
• •Automated Testing: Generate automated tests based on the observed user behavior, ensuring the quality and reliability of your applications.
• •Competitor Analysis: Analyze competitor UIs by recording user interactions and generating code to understand their implementation details.

⚠️ Warning: While Replay can significantly accelerate the development process, it's important to review and customize the generated code to ensure it meets your specific requirements.

The Future of UI Development is Behavior-Driven#

We believe that the future of UI development is behavior-driven. By focusing on user interactions and the underlying logic, we can create more functional, maintainable, and complete applications. Replay is at the forefront of this revolution, empowering developers to build better UIs faster than ever before.

Frequently Asked Questions#

Is Replay free to use?#

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

How is Replay different from v0.dev?#

V0.dev focuses primarily on generating UI components based on text prompts. Replay, on the other hand, analyzes video recordings of user interactions to generate complete applications, including the UI components, event handlers, and data management logic. Replay understands user intent, while v0.dev focuses on visual output based on text input.

What frameworks does Replay support?#

Replay currently supports React, Vue, and Angular. We are constantly adding support for new frameworks.

How accurate is the generated code?#

The accuracy of the generated code depends on the quality of the video recording and the complexity of the UI. In general, Replay can generate highly accurate code for most common UI patterns.

Can I customize the generated code?#

Yes, you can fully customize the generated code using our visual editor or by directly modifying the code in your preferred IDE.

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