Replay AI vs Cursor: Generating REST APIs from UI Demos - Which is Better?

TL;DR: Replay's video-to-code engine excels at generating complete, behavior-driven REST APIs from UI demos, surpassing Cursor's more limited screenshot-based approach.

The promise of AI-powered code generation is seductive: turn ideas into reality with minimal effort. But the reality often falls short. Current tools either produce brittle code snippets or hallucinate functionality. The key differentiator? Understanding intent. That's where video-to-code engines like Replay shine, especially when generating complex functionalities like REST APIs from UI demos. Let's see how Replay stacks up against a more traditional approach using screenshot-to-code tools like Cursor.

The Problem: Static Images Lack Dynamic Context#

Screenshot-to-code tools analyze static images, essentially recreating what they see. This is a fundamentally limited approach. A screenshot of a "Submit" button tells you nothing about what happens when the user clicks it. Does it trigger an API call? What data is sent? What's the expected response? Screenshot-to-code tools can only guess, resulting in incomplete and often incorrect code.

Video, on the other hand, captures the behavior of the user interacting with the UI. This dynamic context is crucial for generating functional code, especially for backend logic like REST APIs.

Replay: Behavior-Driven API Generation#

Replay uses video as the source of truth, employing a "Behavior-Driven Reconstruction" approach. It analyzes user interactions within the video to understand the underlying logic and generate complete, working code, including REST APIs.

Example Scenario: Generating a "Create User" API#

Imagine a UI demo showing a user filling out a form with name, email, and password, then clicking "Create Account."

With a screenshot-to-code tool, you might get a basic HTML form. But with Replay, you get much more:

1. •Form Generation: Replay generates the HTML form with the correct input fields and labels.
2. •API Endpoint Definition: It identifies the "Create Account" button click as a trigger for an API call.
3. •Request Body Extraction: Replay analyzes the form data entered by the user and automatically defines the request body for the API call (name, email, password).
4. •API Call Implementation: It generates the code to make the API call to a specified endpoint (e.g.,
   text

   /api/users
   ).
5. •Database Integration (Optional): With Supabase integration, Replay can generate the code to save the user data to a database.

Here's a simplified example of the generated code:

typescript
// Generated by Replay
const createUser = async (name: string, email: string, password: string) => {
  const response = await fetch('/api/users', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({ name, email, password }),
  });

  if (!response.ok) {
    throw new Error(`HTTP error! status: ${response.status}`);
  }

  return await response.json();
};

This is a complete, working API call, generated directly from the video. Screenshot-to-code tools simply can't achieve this level of functionality.

Step 1: Record Your UI Demo#

Record a short video of yourself interacting with your UI. This video should demonstrate the desired functionality, such as filling out forms, clicking buttons, and navigating between pages.

Step 2: Upload to Replay#

Upload the video to Replay. Replay will automatically analyze the video and generate the code.

Step 3: Review and Refine#

Review the generated code and make any necessary adjustments. Replay provides a visual interface for editing the code and customizing the API endpoints.

Replay vs. Cursor: A Head-to-Head Comparison#

Here's a detailed comparison of Replay and Cursor for generating REST APIs from UI demos:

📝 Note: Cursor can generate UI components from screenshots, but struggles with the dynamic backend logic of APIs.

Why Video-to-Code is the Future#

The key advantage of video-to-code is its ability to capture the context of user interactions. This context is essential for generating complete, working code, especially for complex functionalities like REST APIs.

Here are some key benefits of using Replay:

• •Faster Development: Generate complete code in seconds, reducing development time significantly.
• •Reduced Errors: Automate the process of generating code, reducing the risk of errors.
• •Improved Collaboration: Share videos of UI demos with developers, allowing them to easily understand the desired functionality.
• •Enhanced Understanding: Replay understands what users are trying to achieve, not just what they see.

💡 Pro Tip: When recording your UI demo, be sure to clearly demonstrate the desired functionality and speak clearly about your intentions. This will help Replay generate more accurate and complete code.

⚠️ Warning: While Replay significantly reduces manual coding, it's important to review and refine the generated code to ensure it meets your specific requirements.

The Limitations of Screenshot-to-Code#

Screenshot-to-code tools are useful for generating basic UI components. However, they fall short when it comes to generating complex functionalities like REST APIs. Here's why:

• •Lack of Context: Screenshots lack the dynamic context of user interactions.
• •Limited Understanding: Screenshot-to-code tools only understand what they see, not what users are trying to do.
• •Incomplete Code: Screenshot-to-code tools typically generate incomplete code that requires significant manual coding.

Replay's Unique Features:#

• •Multi-page generation: Replay can follow user flows across multiple pages, generating code for entire applications.
• •Supabase integration: Seamlessly integrate with Supabase to generate database interactions.
• •Style injection: Automatically apply styles to the generated UI.
• •Product Flow maps: Visualize the user flow through the application.

Frequently Asked Questions#

Is Replay free to use?#

Replay offers a free tier with limited usage. Paid plans are available for higher usage and access to advanced features.

How is Replay different from v0.dev?#

v0.dev primarily focuses on generating UI components from text prompts. Replay, on the other hand, generates complete, functional code (including backend logic) from video recordings of UI demos. Replay understands user behavior and intent, allowing it to generate more complete and accurate code.

What types of APIs can Replay generate?#

Replay can generate REST APIs, GraphQL APIs, and other types of APIs. It supports various programming languages and frameworks.

Can Replay handle complex user flows?#

Yes, Replay's multi-page generation feature allows it to handle complex user flows across multiple pages.

How accurate is Replay's code generation?#

Replay's code generation is highly accurate, but it's important to review and refine the generated code to ensure it meets your specific requirements. The accuracy depends on the clarity and completeness of the video recording.

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