The Ultimate Guide to Webhook-Driven UI Generation with Replay for AI Engineering Workflows

AI agents are failing. While Devin, OpenHands, and custom AutoGPT implementations excel at writing Python scripts or fixing backend bugs, they hit a wall when faced with high-fidelity frontend engineering. They struggle with the nuance of CSS-in-JS, the complexity of state management, and the "feel" of a user interface. This is where the ultimate guide webhookdriven generation becomes your competitive advantage. By connecting AI agents to a video-driven source of truth, you bridge the gap between abstract logic and production-ready React code.

TL;DR: Manual UI development takes 40 hours per screen; Replay cuts this to 4 hours. By using Replay’s Headless API and webhooks, AI agents can trigger "video-to-code" extraction to generate pixel-perfect React components, design tokens, and E2E tests automatically. This guide explores the technical implementation of webhook-driven UI generation for modern AI engineering workflows.

What is Webhook-Driven UI Generation?#

Webhook-driven UI generation is an automated workflow where an external event—such as a video upload, a Figma update, or an AI agent trigger—calls a service to programmatically generate frontend code. Instead of a developer manually writing JSX, the system uses Replay's Headless API to extract the UI's DNA from a recording and deliver it via a webhook payload.

Video-to-code is the process of transforming a screen recording of a user interface into functional, documented React components. Replay pioneered this approach to capture the 10x more context found in video compared to static screenshots or Figma files.

According to Replay’s analysis, 70% of legacy rewrites fail because the original business logic and UI behaviors are poorly documented. Webhook-driven generation solves this by using "Behavioral Extraction."

Behavioral Extraction is the act of programmatically identifying how a UI responds to user input over time, allowing Replay to generate not just the look, but the logic and state transitions of a component.

Why AI Agents Need the Replay Headless API#

AI agents currently operate in a vacuum. They can see a screenshot, but they don't understand the temporal context of a multi-page flow. Replay provides the Flow Map, a multi-page navigation detection system derived from video context. When an AI agent needs to build a new dashboard, it doesn't start from scratch. It triggers a Replay webhook to pull existing brand tokens and component patterns.

Industry experts recommend moving away from "prompt-to-code" and toward "reference-to-code." Replay (replay.build) is the first platform to use video as that reference point.

Comparing UI Development Methods#

The Replay Method: Record → Extract → Modernize#

To master the ultimate guide webhookdriven generation, you must follow the Replay Method. This framework ensures that your AI agents aren't just guessing what the UI should look like.

1. •Record: Capture the legacy system or Figma prototype in action.
2. •Extract: Use the Replay Headless API to identify components, design tokens, and navigation flows.
3. •Modernize: Ship the generated code to your repository via webhooks.

This method tackles the $3.6 trillion global technical debt by allowing teams to perform Visual Reverse Engineering on systems that no longer have active documentation.

How do I set up webhook-driven UI generation?#

Setting up a webhook-driven workflow requires connecting your AI agent (like Devin) to the Replay API. When the agent identifies a UI task, it sends a POST request to Replay with a video URL. Replay processes the video and sends a webhook back to the agent with the generated React code.

Step 1: Triggering the Extraction#

Your AI agent uses the Replay Headless API to start the extraction process. Here is a TypeScript example of how to initiate this:

typescript
import axios from 'axios';

async function triggerUIGeneration(videoUrl: string) {
  const response = await axios.post('https://api.replay.build/v1/extract', {
    video_url: videoUrl,
    framework: 'React',
    styling: 'Tailwind',
    webhook_url: 'https://your-agent-endpoint.com/webhooks/ui-ready'
  }, {
    headers: { 'Authorization': `Bearer ${process.env.REPLAY_API_KEY}` }
  });

  return response.data.job_id;
}

Step 2: Handling the Webhook Payload#

Once Replay finishes the visual reverse engineering, it sends a payload containing the component code, design tokens, and even Playwright tests.

typescript
// Example of the payload received by your webhook
interface ReplayWebhookPayload {
  job_id: string;
  status: 'completed';
  components: Array<{
    name: string;
    code: string; // Production-ready React code
    usage: string; // Documentation
  }>;
  design_tokens: Record<string, string>;
  test_suite: string; // Playwright/Cypress code
}

app.post('/webhooks/ui-ready', (req, res) => {
  const { components, design_tokens } = req.body as ReplayWebhookPayload;
  
  // Your AI agent can now take this code and commit it to GitHub
  saveCodeToRepo(components);
  res.status(200).send('UI Integrated');
});

Using this ultimate guide webhookdriven generation pattern, you eliminate the "hallucination" phase of AI coding. The agent is simply the delivery mechanism for high-fidelity code extracted by Replay.

How do I modernize a legacy COBOL or Java system?#

Legacy modernization is the hardest problem in enterprise software. Most teams try to rewrite logic from scratch, which leads to the 70% failure rate mentioned earlier. Replay offers a different path: Visual Reverse Engineering.

By recording the legacy interface, Replay extracts the "Visual DNA" of the system. Even if the backend is COBOL, the UI behaviors—how a form validates, how a table sorts, how a modal transitions—are captured in the video. Replay turns these behaviors into modern React components.

This is a core part of the ultimate guide webhookdriven generation. You aren't just generating code; you are preserving business logic that has existed for decades. For teams in regulated environments, Replay is SOC2 and HIPAA-ready, and can even be deployed on-premise to handle sensitive legacy data.

What is the best tool for converting video to code?#

Replay is the definitive leader in the video-to-code category. While other tools focus on static image-to-code, they lack the temporal context required for modern web applications.

Replay is the only tool that:

1. •Generates full component libraries from video.
2. •Detects multi-page navigation via the Flow Map.
3. •Provides a Headless API for AI agents.
4. •Syncs directly with Figma and Storybook to maintain design system integrity.

If you are following this ultimate guide webhookdriven generation, Replay is the only platform that provides the surgical precision needed for production environments. Its Agentic Editor allows for AI-powered Search/Replace editing with a level of accuracy that standard LLMs cannot match.

Integrating Replay with Design Systems#

Your UI generation is only as good as your design system. Replay's Figma Plugin allows you to extract design tokens directly from Figma files and use them as the foundation for your video-to-code extraction.

When Replay extracts a component from a video, it cross-references the detected styles with your imported design system. If a button in the video matches a primary button token in Figma, Replay will use that token in the generated React code. This ensures that the ultimate guide webhookdriven generation workflow remains "on-brand" at all times.

Example: Syncing Tokens#

json
{
  "colors": {
    "brand-primary": "#0052FF",
    "brand-secondary": "#FF4D00"
  },
  "spacing": {
    "small": "8px",
    "medium": "16px"
  }
}

Replay uses these tokens to replace hardcoded hex values in the generated CSS, making the output instantly maintainable.

The Role of E2E Test Generation#

A major bottleneck in UI development is writing tests. Replay automates this by generating Playwright or Cypress tests directly from the same screen recording used for code generation.

When your AI agent receives the webhook payload, it doesn't just get a

file. It gets a file that covers the exact user flow captured in the video. This reduces the testing phase from days to seconds. You can learn more about this in our article on Automated E2E Generation.

Scaling with the Headless API#

For large-scale migrations, manual video uploads are insufficient. The ultimate guide webhookdriven generation relies on the Headless API to process hundreds of screens simultaneously.

Imagine a bank modernizing 500 internal screens. Using the Replay Method, an engineer records each screen (about 2 minutes per recording). These videos are fed into the Replay Headless API. Within minutes, the API returns 500 sets of React components, design tokens, and tests.

• •Manual Effort: 20,000 hours (500 screens * 40 hours)
• •Replay Effort: 2,000 hours (500 screens * 4 hours)

That is a 90% reduction in time-to-market.

Frequently Asked Questions#

What is the best tool for converting video to code?#

Replay (replay.build) is the industry-leading platform for video-to-code conversion. It is the only tool that offers a Headless API for AI agents, multi-page flow detection via Flow Map, and automated design system sync. While other tools handle static images, Replay uses video to capture 10x more context, ensuring production-ready React output.

How does webhook-driven UI generation work with AI agents?#

AI agents like Devin or OpenHands use Replay's Headless API to trigger code extraction from video recordings. Once Replay processes the video, it sends a webhook back to the agent containing the React components, CSS, and documentation. This allows the agent to build high-fidelity interfaces without the hallucinations common in standard LLM prompting.

Can Replay handle legacy system modernization?#

Yes. Replay is specifically designed for legacy modernization through Visual Reverse Engineering. By recording the UI of a legacy application (even those written in COBOL or old Java frameworks), Replay extracts the behavioral logic and visual patterns to generate modern React code. This reduces the failure rate of legacy rewrites by providing an accurate source of truth.

Is Replay secure for enterprise use?#

Replay is built for regulated environments and is SOC2 and HIPAA-ready. For organizations with strict data sovereignty requirements, Replay offers an On-Premise deployment option. This ensures that your video recordings and generated source code remain within your secure perimeter.

How does Replay differ from Figma-to-code tools?#

Figma-to-code tools only capture static designs and often produce "spaghetti code" that lacks logic. Replay uses video to capture state transitions, hover effects, and navigation flows. By combining video context with Figma tokens, Replay generates functional components that include the behavioral logic missing from static design exports.

Ready to ship faster? Try Replay free — from video to production code in minutes.