Replay vs. Lovable.dev: Which AI Code Generator Handles Complex Form Logic in 2026?

TL;DR: Replay leverages video analysis and behavior-driven reconstruction to accurately generate code for complex forms, surpassing Lovable.dev's screenshot-based approach in understanding user intent.

AI-powered code generation tools are rapidly evolving. While many promise to turn designs into functional code, the devil is in the details – especially when dealing with complex form logic. In 2026, two prominent players are Replay and Lovable.dev. Let's dive into a head-to-head comparison, focusing on their ability to handle intricate forms and the underlying technologies that make them tick.

Understanding the Challenge: Complex Form Logic#

Forms are the lifeblood of user interaction. Simple forms are easy to generate from static images. But complex forms with conditional logic, dynamic validation, and multi-page flows require a deeper understanding of user behavior. Generating code that accurately reflects this behavior is a significant challenge for AI-powered tools.

Consider a multi-step application form with the following requirements:

• •Conditional Fields: Display different fields based on the user's selection (e.g., show "Company Name" field only if the user selects "Business" as their account type).
• •Dynamic Validation: Validate input based on other fields (e.g., ensure the "End Date" is after the "Start Date").
• •Multi-Page Flow: Guide the user through a series of steps, saving progress along the way.

Replay vs. Lovable.dev: A Feature Breakdown#

Lovable.dev, like many other tools, relies on screenshot-to-code conversion. While this approach can be effective for simple UIs, it struggles with dynamic behavior. Replay, on the other hand, analyzes video recordings of user interactions, enabling it to understand the intent behind each action.

How Replay Tackles Complex Form Logic: Behavior-Driven Reconstruction#

Replay's core innovation lies in its "Behavior-Driven Reconstruction" engine. Instead of merely translating pixels into code, Replay analyzes the video to understand what the user is trying to achieve. This allows it to accurately reconstruct complex form logic.

Here's how it works:

1. •Video Analysis: Replay analyzes the video recording, identifying user interactions such as clicks, keystrokes, and form submissions.
2. •Intent Inference: Using Gemini, Replay infers the user's intent based on the sequence of actions. For example, if a user selects "Business" as their account type and then fills out the "Company Name" field, Replay understands that the "Company Name" field is conditionally displayed based on the "Business" selection.
3. •Code Generation: Replay generates code that accurately reflects the inferred intent. This includes conditional statements, validation rules, and multi-page navigation.

Step 1: Recording the Form Interaction#

Start by recording a video of a user interacting with the form. Make sure to capture all the different scenarios, including conditional field displays, validation errors, and successful form submissions.

Step 2: Uploading to Replay#

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

Step 3: Reviewing and Refining the Code#

Review the generated code and make any necessary adjustments. Replay provides a visual editor that allows you to easily modify the code and see the changes in real-time.

Step 4: Integrating with Your Project#

Download the generated code and integrate it into your project. Replay supports various frameworks and libraries, including React, Angular, and Vue.js.

Code Example: Conditional Field Display#

Here's an example of how Replay handles conditional field display in React:

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

const MyForm = () => {
  const [accountType, setAccountType] = useState('');
  const [companyName, setCompanyName] = useState('');

  const handleAccountTypeChange = (event: React.ChangeEvent<HTMLSelectElement>) => {
    setAccountType(event.target.value);
  };

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

  return (
    <div>
      <label htmlFor="accountType">Account Type:</label>
      <select id="accountType" value={accountType} onChange={handleAccountTypeChange}>
        <option value="">Select...</option>
        <option value="Personal">Personal</option>
        <option value="Business">Business</option>
      </select>

      {accountType === 'Business' && (
        <div>
          <label htmlFor="companyName">Company Name:</label>
          <input type="text" id="companyName" value={companyName} onChange={handleCompanyNameChange} />
        </div>
      )}
    </div>
  );
};

export default MyForm;

In this example, Replay automatically generates the conditional rendering logic (

) based on the video analysis. Lovable.dev, relying solely on visual information, would struggle to infer this behavior.

Code Example: Dynamic Validation#

Here's an example of dynamic validation using React Hook Form, which Replay can generate:

typescript
import React from 'react';
import { useForm } from 'react-hook-form';

interface FormData {
  startDate: string;
  endDate: string;
}

const DateForm = () => {
  const { register, handleSubmit, formState: { errors } } = useForm<FormData>();

  const onSubmit = (data: FormData) => {
    console.log(data);
  };

  return (
    <form onSubmit={handleSubmit(onSubmit)}>
      <div>
        <label htmlFor="startDate">Start Date:</label>
        <input type="date" id="startDate" {...register("startDate", { required: "Start date is required" })} />
        {errors.startDate && <span>{errors.startDate.message}</span>}
      </div>

      <div>
        <label htmlFor="endDate">End Date:</label>
        <input
          type="date"
          id="endDate"
          {...register("endDate", {
            required: "End date is required",
            validate: (value) => {
              const startDate = new Date(document.getElementById("startDate")!.value);
              const endDate = new Date(value);
              return endDate > startDate || "End date must be after start date";
            },
          })}
        />
        {errors.endDate && <span>{errors.endDate.message}</span>}
      </div>

      <button type="submit">Submit</button>
    </form>
  );
};

export default DateForm;

Replay can infer the relationship between the "Start Date" and "End Date" fields from the video and generate the appropriate validation logic using

.

💡 Pro Tip: For best results, ensure your video recordings are clear and well-structured. Clearly demonstrate all possible scenarios and edge cases.

Real-World Use Cases#

Replay's ability to handle complex form logic opens up a wide range of use cases:

• •Rapid Prototyping: Quickly generate working prototypes from user interaction videos.
• •Legacy System Modernization: Reconstruct old UIs from screen recordings, even if the original source code is lost.
• •User Research and A/B Testing: Analyze user behavior to identify areas for improvement and generate code for A/B testing variations.

⚠️ Warning: Replay's accuracy depends on the quality of the video recording. Ensure the video is clear and captures all relevant user interactions.

The Power of Supabase Integration#

Replay also offers seamless integration with Supabase, allowing you to easily connect your generated code to a backend database. This significantly accelerates the development process, especially for data-driven applications.

📝 Note: Replay's Supabase integration allows you to automatically generate database schemas and API endpoints based on the form structure.

Key Benefits of Replay:#

• •Accuracy: Accurately reconstructs complex form logic from video recordings.
• •Speed: Significantly accelerates the development process.
• •Flexibility: Supports various frameworks and libraries.
• •Ease of Use: Simple and intuitive interface.
• •Integration: Seamless integration with Supabase and other tools.
• •Behavior-Driven: Captures user intent, not just visual appearance.
• •Multi-Page Support: Generates entire product flows, not just single screens.

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 primarily focuses on generating UI components from text prompts. Replay, on the other hand, analyzes video recordings to understand user behavior and reconstruct entire applications, including complex form logic. V0.dev is excellent for generating individual components; Replay excels at building complete, interactive experiences.

What video formats are supported?#

Replay supports a wide range of video formats, including MP4, MOV, and WebM.

What frameworks are supported?#

Replay supports React, Angular, Vue.js, and other popular frameworks.

How secure is my video data?#

Replay uses industry-standard security measures to protect your video data. All videos are encrypted in transit and at rest.

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