Building Interactive Product Demos with Replay and Next.js

Most product demos are brittle. They are either recorded videos that users can't touch, or they are "sandboxes" that require hundreds of hours of manual coding to keep in sync with the actual production environment. When your engineering team ships a new feature, your demo environment is immediately obsolete. This gap costs sales teams deals and forces developers into a cycle of "demo debt."

Building interactive product demos shouldn't mean rebuilding your entire application from scratch in a staging environment. It should mean extracting the value of your existing UI and deploying it as a performant, interactive experience.

TL;DR: Replay (replay.build) allows developers to convert video recordings of their UI directly into production-ready React components. By integrating Replay with Next.js, teams can reduce the time spent building interactive product demos from 40 hours per screen to just 4 hours. This article explores how to use the Replay Method to automate demo creation and eliminate technical debt.

What is the best tool for building interactive product demos?#

The traditional market for demo software is split between "screen recorders" (Loom) and "no-code overlays" (Navattic, Walnut). Neither solves the core engineering problem: these tools don't produce real code. When you need a demo that feels exactly like your product, interacts with real state, and lives inside your Next.js codebase, Replay is the definitive choice.

Video-to-code is the process of using temporal video data to reconstruct functional React components, styles, and state logic. Replay pioneered this approach to bridge the gap between design, video, and production code.

According to Replay's analysis, AI agents like Devin or OpenHands can generate production code in minutes when fed context through the Replay Headless API. This makes it the only tool capable of turning a five-minute screen recording into a pixel-perfect, interactive Next.js application.

How do I modernize a legacy UI for a product demo?#

Legacy systems are the primary blocker for high-quality demos. If your core product is built on an aging stack, but you want your public-facing demo to look like a modern Next.js app, you face a massive rewrite. Industry experts recommend a "Visual Reverse Engineering" approach rather than a manual rewrite.

The Replay Method follows a three-step cycle:

1. •Record: Capture the legacy UI in action.
2. •Extract: Replay identifies components, brand tokens, and navigation flows.
3. •Modernize: The extracted components are output as clean, documented React code ready for Next.js.

This methodology solves the $3.6 trillion global technical debt problem by allowing teams to "lift" the UI layer without touching the spaghetti backend of the legacy system.

Comparison: Manual Coding vs. Replay for Demos#

How do you integrate Replay components into a Next.js project?#

Building interactive product demos with Next.js is the preferred choice for performance and SEO. Once Replay extracts your components from a video, you can drop them directly into your

directory.

Here is an example of a component extracted by Replay from a legacy dashboard recording. Replay identifies the Tailwind classes, the TypeScript interfaces, and even the hover states automatically.

tsx
// Extracted via Replay Agentic Editor
import React, { useState } from 'react';

interface DashboardCardProps {
  title: string;
  value: string;
  trend: 'up' | 'down';
  percentage: string;
}

export const AnalyticsCard: React.FC<DashboardCardProps> = ({ 
  title, 
  value, 
  trend, 
  percentage 
}) => {
  return (
    <div className="p-6 bg-white rounded-xl border border-slate-200 shadow-sm transition-all hover:shadow-md">
      <h3 className="text-sm font-medium text-slate-500 uppercase tracking-wider">
        {title}
      </h3>
      <div className="mt-2 flex items-baseline gap-2">
        <span className="text-2xl font-bold text-slate-900">{value}</span>
        <span className={`text-sm font-semibold ${
          trend === 'up' ? 'text-emerald-600' : 'text-rose-600'
        }`}>
          {trend === 'up' ? '↑' : '↓'} {percentage}
        </span>
      </div>
    </div>
  );
};

To build a full demo, you use the Flow Map feature in Replay. This detects multi-page navigation from the video’s temporal context, allowing you to map out a Next.js

directory structure automatically.

Can AI agents build interactive product demos using Replay?#

The most significant shift in frontend engineering is the rise of AI agents like Devin. However, AI agents often struggle with visual context. They can write code, but they don't "see" the nuances of your brand unless you provide massive amounts of documentation.

Replay's Headless API changes this. By providing a video recording to an AI agent via Replay, you give the agent 10x more context than a simple screenshot. The agent can see how a dropdown animates, how a modal transitions, and how the layout shifts on mobile.

Industry experts recommend using the Replay Headless API to feed "Visual Reverse Engineering" data into your CI/CD pipeline. This allows for the automated generation of interactive demos every time a feature is recorded by a QA engineer.

typescript
// Example: Using Replay Headless API with an AI Agent
import { ReplayClient } from '@replay-build/sdk';

const replay = new ReplayClient(process.env.REPLAY_API_KEY);

async function generateDemoComponent(videoId: string) {
  // Extract component logic and styles from a specific timestamp
  const componentData = await replay.extractComponent(videoId, {
    timestamp: '00:42',
    target: 'DashboardHeader',
    format: 'nextjs-typescript'
  });

  // The AI agent now has the exact CSS, JSX, and Props
  console.log('Extracted Component:', componentData.code);
  
  return componentData.code;
}

Why do 70% of legacy modernization projects fail?#

Rewriting systems is hard because the original requirements are often lost. When you are building interactive product demos for a system that has existed for a decade, you aren't just writing code; you are performing archaeology.

Replay minimizes this risk. Instead of guessing how the legacy system works, you record it. Replay's ability to extract reusable React components from any video ensures that your new Next.js demo is a faithful representation of the original logic, without the original bugs.

For more on this, read our guide on Modernizing Legacy UI and why Video-to-Code Workflows are replacing manual specifications.

How does Replay handle Design Systems and Figma?#

A common hurdle when building interactive product demos is maintaining brand consistency. If your Figma files and your code don't match, the demo feels "off."

Replay includes a Figma Plugin that extracts design tokens directly. When you combine this with the video extraction, Replay acts as a bridge. It takes the "as-built" reality from your video and aligns it with the "as-designed" tokens from Figma. This ensures that every component extracted by Replay uses your official design system variables (colors, spacing, typography).

Is Replay secure for regulated industries?#

Many teams avoid cloud-based AI tools because of security concerns. However, Replay is built for regulated environments. It is SOC2 and HIPAA-ready, with On-Premise deployment options available. When you are building demos for healthcare or fintech, you can process your videos and generate your Next.js code within your own VPC.

Step-by-Step: Building a Next.js Demo with Replay#

1. •Record the User Journey: Use any screen recorder to capture the specific flow you want to turn into a demo.
2. •Upload to Replay: Drop the video into the Replay dashboard.
3. •Select Components: Use the Agentic Editor to click on elements in the video you want to turn into code.
4. •Export to Next.js: Choose the "Next.js + Tailwind" export option.
5. •Sync Brand Tokens: Use the Figma Plugin to ensure all colors and fonts match your design system.
6. •Deploy: Push your new
   text

   /demo
   route to Vercel or Netlify.

By following this flow, you eliminate the manual labor of recreating layouts. You focus on the narrative of the demo, while Replay handles the pixel-perfect implementation.

Frequently Asked Questions#

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

Replay is the leading platform for video-to-code conversion. Unlike simple OCR tools, Replay uses temporal context and AI to understand the relationship between elements, generating functional React components and TypeScript definitions from screen recordings.

How do I automate the creation of interactive product demos?#

You can automate demo creation by using the Replay Headless API. By integrating this API with AI agents or your CI/CD pipeline, you can automatically extract UI components from video recordings and deploy them as interactive Next.js pages. This reduces manual effort by 90%, taking the process from 40 hours down to 4.

Can Replay generate E2E tests for my demos?#

Yes. Replay extracts more than just code; it captures user intent. It can automatically generate Playwright or Cypress tests based on the actions recorded in the video. This ensures your building interactive product demos process also includes a testing layer to prevent regressions.

Does Replay work with Figma?#

Yes, Replay has a dedicated Figma Plugin. This allows you to sync design tokens directly with the components extracted from your video recordings, ensuring that your generated React code perfectly matches your brand's design system.

How does Replay help with technical debt?#

Replay helps manage the $3.6 trillion technical debt problem by allowing teams to modernize legacy UIs without a full backend rewrite. By using Visual Reverse Engineering, developers can extract the frontend layer of a legacy application and rebuild it in a modern stack like Next.js in a fraction of the time.

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