Replay vs. Lovable.dev: Which is the Best For Generating UI Code with Complex Forms? (2026)

TL;DR: Replay offers a superior solution for generating UI code with complex forms by analyzing video of user behavior, unlike Lovable.dev which relies on static screenshots, resulting in more accurate and functional code reconstruction.

The promise of AI-powered UI code generation is tantalizing: turn designs or even existing interfaces into working code with minimal effort. Two tools vying for dominance in this space are Replay and Lovable.dev. While both aim to streamline UI development, their approaches and capabilities differ significantly, especially when dealing with the complexities of forms. Let's dive into a head-to-head comparison, focusing on the challenges inherent in form generation.

The Formidable Challenge of Forms#

Forms are the lifeblood of interactive web applications. They handle user input, drive data flow, and dictate user experience. Generating code for complex forms, however, presents unique challenges:

• •Dynamic Behavior: Forms often involve conditional logic, validation rules, and dynamic field updates based on user input. Screenshot-based tools struggle to capture this dynamic nature.
• •State Management: Tracking form state (e.g., which fields are filled, which are valid) is crucial. This requires understanding the sequence of user actions, not just the final result.
• •Data Dependencies: Some form fields depend on data fetched from external APIs or databases. The generated code needs to handle these dependencies correctly.
• •Accessibility: Ensuring forms are accessible to users with disabilities is paramount. This involves generating semantic HTML, ARIA attributes, and proper keyboard navigation.

Replay vs. Lovable.dev: A Detailed Comparison#

Let's examine how Replay and Lovable.dev tackle these challenges:

As you can see, the core difference lies in the input type and subsequent behavior analysis. Lovable.dev operates on static screenshots, while Replay leverages video analysis. This seemingly small difference has profound implications for handling complex forms.

Lovable.dev: The Screenshot-to-Code Approach#

Lovable.dev excels at generating code from static UI designs. It can identify UI elements, infer their structure, and generate corresponding HTML and CSS. It also offers integrations with popular frameworks and styling libraries.

However, its reliance on screenshots limits its ability to handle dynamic behavior. For complex forms, this means:

• •Missing Validation Rules: Lovable.dev can identify input fields but cannot infer the validation rules associated with them. You'll need to manually add these rules to the generated code.
• •Incorrect State Management: Because it doesn't track user actions, Lovable.dev cannot accurately represent the form's state. This can lead to bugs and unexpected behavior.
• •Limited Data Dependencies: While it can identify API endpoints, Lovable.dev cannot automatically generate code to fetch and populate form fields with data.

⚠️ Warning: Expect significant manual intervention when using Lovable.dev for complex forms. You'll likely spend more time debugging and modifying the generated code than you would writing it from scratch.

Replay: Behavior-Driven Reconstruction#

Replay takes a fundamentally different approach. By analyzing video recordings of user interactions, it understands how users interact with the UI, not just what the UI looks like. This "Behavior-Driven Reconstruction" allows Replay to:

• •Infer Validation Rules: By observing user input and error messages, Replay can infer the validation rules associated with each form field.
• •Track Form State: Replay understands the sequence of user actions and can accurately represent the form's state at any given point in time.
• •Handle Data Dependencies: Replay can identify API calls made during form interactions and generate code to fetch and populate form fields with data.
• •Generate Multi-Page Flows: Unlike tools limited to single screenshots, Replay understands user navigation across multiple pages, allowing it to generate complete product flows.

Consider this scenario: a user fills out a multi-step form with conditional logic. Some fields are only displayed based on previous selections. Replay can capture this entire flow and generate code that accurately reflects the form's dynamic behavior. Lovable.dev, on the other hand, would only be able to generate code for the visible elements in each screenshot, leaving you to manually stitch together the logic.

Here's a simplified example. Imagine a form where selecting "Yes" on a radio button reveals an additional text field.

With Replay, the generated code might look like this:

typescript
import React, { useState } from 'react';

const ConditionalForm = () => {
  const [showTextField, setShowTextField] = useState(false);

  const handleRadioChange = (event: React.ChangeEvent<HTMLInputElement>) => {
    setShowTextField(event.target.value === 'yes');
  };

  return (
    <div>
      <label>
        <input
          type="radio"
          value="yes"
          checked={showTextField}
          onChange={handleRadioChange}
        />
        Yes
      </label>
      <label>
        <input
          type="radio"
          value="no"
          checked={!showTextField}
          onChange={handleRadioChange}
        />
        No
      </label>

      {showTextField && (
        <div>
          <label htmlFor="additionalInfo">Additional Information:</label>
          <input type="text" id="additionalInfo" />
        </div>
      )}
    </div>
  );
};

export default ConditionalForm;

Replay understands the relationship between the radio button selection and the visibility of the text field, capturing the user's intent from the video. Lovable.dev would likely only generate the basic HTML structure without the conditional rendering logic, requiring you to add it manually.

Supabase Integration & Style Injection#

Both Replay and Lovable.dev offer Supabase integration, allowing you to easily connect your generated code to a backend database. They also support style injection, enabling you to customize the look and feel of your UI using CSS or styling libraries. This is crucial for maintaining design consistency and branding.

Product Flow Maps#

Replay offers a unique "Product Flow Maps" feature. By analyzing video recordings of entire user journeys, Replay can generate visual diagrams that illustrate how users navigate through your application. This is invaluable for understanding user behavior and identifying areas for improvement. Lovable.dev lacks this capability.

💡 Pro Tip: Use Replay's Product Flow Maps to identify common user paths and optimize your form design for better conversion rates.

Step-by-Step: Generating a Complex Form with Replay#

Let's walk through the process of generating a complex form with Replay:

Step 1: Record the User Interaction#

Use a screen recording tool (or Replay's built-in recorder) to capture a user filling out the form. Make sure to demonstrate all possible scenarios, including validation errors, conditional logic, and data dependencies.

Step 2: Upload the Video to Replay#

Upload the video to the Replay platform. Replay will automatically analyze the video and reconstruct the UI code.

Step 3: Review and Refine the Generated Code#

Review the generated code to ensure it accurately reflects the form's behavior. You can use Replay's code editor to make any necessary adjustments.

Step 4: Integrate with Your Project#

Copy the generated code into your project and connect it to your backend database using the Supabase integration.

📝 Note: While Replay significantly reduces the amount of manual coding required, some refinement may still be necessary, especially for highly complex forms.

Addressing Common Concerns#

Some developers might be skeptical of video-to-code technology. Here are some common concerns and how Replay addresses them:

• •Accuracy: "How accurate is the generated code?" Replay's accuracy is significantly higher than screenshot-based tools, especially for dynamic UIs. However, it's essential to review and refine the generated code to ensure it meets your specific requirements.
• •Security: "Is it safe to upload video recordings of user interactions?" Replay uses industry-standard security measures to protect your data. All video recordings are encrypted and stored securely.
• •Performance: "Will the generated code be performant?" Replay generates clean and efficient code that is optimized for performance. However, it's important to profile and optimize your application as a whole to ensure optimal performance.

Frequently Asked Questions#

Is Replay free to use?#

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

How is Replay different from v0.dev?#

v0.dev is a text-to-code AI tool, whereas Replay uses video as its source of truth. This allows Replay to understand user behavior and generate more accurate and functional code, especially for dynamic UIs.

What frameworks does Replay support?#

Replay currently supports React, Vue, and Angular. Support for other frameworks is planned for the future.

How does Replay handle sensitive data in video recordings?#

Replay provides tools to redact sensitive data from video recordings before uploading them. This ensures that your users' privacy is protected.

Can Replay generate tests for the generated code?#

Yes, Replay can generate basic unit tests for the generated code. More advanced test generation capabilities are planned for the future.

The Verdict#

While both Lovable.dev and Replay offer valuable tools for UI code generation, Replay's behavior-driven reconstruction approach provides a clear advantage when dealing with complex forms. By analyzing video recordings of user interactions, Replay can generate more accurate, functional, and maintainable code than screenshot-based tools. If you're serious about streamlining your UI development workflow and tackling the challenges of form generation, Replay is the superior choice.

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