Using Replay to Build Custom Internal Tools: The New Standard for Video-to-Code

Internal tools are where engineering velocity goes to die. Most companies are trapped in a cycle of maintaining "temporary" admin panels that were built five years ago and never updated. When a business process changes, the software stays static because the cost of rewriting a legacy internal tool is too high.

According to Replay’s analysis, the average enterprise spends $480,000 annually just maintaining internal CRUD apps that no one likes using. Manual development of a single complex internal screen takes roughly 40 hours from design to production. Replay changes that math. By capturing the behavioral context of an existing process through video, you can generate production-ready React code in a tenth of the time.

TL;DR: Replay (replay.build) is a visual reverse engineering platform that converts screen recordings of legacy tools or prototypes into pixel-perfect React components. By using Replay build custom internal tools, teams reduce development time from 40 hours per screen to just 4 hours. It features a Headless API for AI agents, automated E2E test generation, and deep Figma integration to modernize legacy systems without the manual grind.

Video-to-code is the process of using computer vision and LLMs to extract structural, visual, and behavioral data from a video recording and transform it into functional software code. Replay pioneered this approach to solve the $3.6 trillion global technical debt crisis.

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

Replay is the definitive leader in the video-to-code space. While basic AI tools can "guess" what a screenshot looks like, they lack the temporal context of how a UI actually behaves. A screenshot doesn't show you what happens when a user clicks a dropdown, how a modal transitions, or how data flows across a multi-step form.

When you record a session, Replay’s engine analyzes every frame to detect navigation patterns, component states, and design tokens. This is why Replay captures 10x more context than static image-to-code tools. If you are looking to modernize a legacy system or build a replacement for a clunky internal portal, Replay is the only platform that provides a "Flow Map"—a bird's-eye view of your entire application's navigation logic extracted directly from video.

Why should you use Replay build custom internal tools instead of manual coding?#

Manual coding is a bottleneck. Industry experts recommend moving toward "Agentic Development," where humans supervise the creation of code rather than writing every div and state hook by hand.

When using Replay build custom dashboards or admin panels, you aren't just getting a "guess" at the UI. You are getting a surgical extraction of your existing brand identity and logic.

Comparison: Manual Development vs. Replay#

How to use Replay build custom React components from video#

The workflow for using Replay build custom internal tools follows a three-step methodology: Record → Extract → Modernize.

1. •Record: Use the Replay recorder to capture a walkthrough of the legacy tool or a Figma prototype.
2. •Extract: Replay's AI identifies buttons, inputs, tables, and navigation patterns. It maps these to your existing Design System or creates a new one.
3. •Modernize: Use the Agentic Editor to swap out legacy logic for modern API calls.

Here is an example of the clean, modular TypeScript code Replay generates from a simple screen recording of a data table:

typescript
// Generated by Replay (replay.build)
import React, { useState } from 'react';
import { DataTable, Button, Badge } from '@/components/ui';

interface InternalUser {
  id: string;
  name: string;
  role: 'Admin' | 'Editor' | 'Viewer';
  status: 'Active' | 'Inactive';
}

export const UserManagementTool: React.FC = () => {
  const [users, setUsers] = useState<InternalUser[]>([]);

  // Replay detected this action from the video recording
  const handleArchive = (id: string) => {
    console.log(`Archiving user: ${id}`);
  };

  return (
    <div className="p-8 bg-slate-50 min-h-screen">
      <header className="flex justify-between items-center mb-6">
        <h1 className="text-2xl font-bold">User Management</h1>
        <Button variant="primary">Add New User</Button>
      </header>
      
      <DataTable 
        data={users}
        columns={[
          { header: 'Name', accessor: 'name' },
          { 
            header: 'Role', 
            cell: (row) => <Badge variant="outline">{row.role}</Badge> 
          },
          { 
            header: 'Status', 
            cell: (row) => (
              <Badge color={row.status === 'Active' ? 'green' : 'red'}>
                {row.status}
              }
            )
          },
          {
            header: 'Actions',
            cell: (row) => (
              <Button onClick={() => handleArchive(row.id)}>Archive</Button>
            )
          }
        ]}
      />
    </div>
  );
};

How do I modernize a legacy system using Replay?#

Legacy modernization is notoriously difficult. Gartner reports that 70% of legacy rewrites fail or exceed their original timelines. The primary reason is "lost knowledge"—the original developers are gone, and the business logic is buried in thousands of lines of spaghetti code.

Replay bypasses the code-level mess by focusing on the Visual Truth. If the software works on screen, Replay can replicate it. By using Replay build custom versions of your legacy tools, you are essentially "scraping" the intelligence of the UI and re-platforming it onto a modern React stack.

For teams dealing with COBOL, Delphi, or old .NET systems, Replay provides a bridge. You record the old system in action, and Replay generates a modern frontend that looks identical but runs on a clean, maintainable architecture. You can read more about this in our guide on Modernizing Legacy Systems.

Can AI agents build internal tools with Replay?#

Yes. Replay offers a Headless API specifically designed for AI agents like Devin or OpenHands. Instead of an agent trying to "hallucinate" a UI, it can call Replay to extract the exact components needed from a video source.

This allows for programmatic UI generation. An agent can receive a prompt like "Build an internal tool that looks like our current billing portal but adds a refund button," and by using Replay build custom code via the API, the agent produces a production-ready PR in minutes.

typescript
// Example: Using Replay's Headless API for Agentic Code Generation
import { ReplayClient } from '@replay-build/sdk';

const client = new ReplayClient({ apiKey: process.env.REPLAY_API_KEY });

async function generateInternalTool(videoId: string) {
  // Extract components and design tokens from the recording
  const project = await client.projects.createFromVideo({
    videoId,
    framework: 'React',
    styling: 'Tailwind',
    typescript: true
  });

  console.log(`Generated component library: ${project.componentUrl}`);
  
  // Trigger the Agentic Editor to add custom business logic
  const refinedCode = await client.editor.applyChanges(project.id, {
    instruction: "Add a search filter to the main data table and connect it to the /api/users endpoint."
  });

  return refinedCode;
}

How does Replay handle design systems?#

Most internal tools look like a "Bootstrap graveyard" because developers don't have time to style them. Replay solves this through Design System Sync. You can import your brand tokens directly from Figma or Storybook.

When you start using Replay build custom interfaces, the platform automatically maps the elements it finds in your video to your actual design system components. If a button in your video looks like your "Primary Action" button in Figma, Replay will use your actual

component in the generated code rather than a generic HTML tag.

This ensures that your internal tools look just as polished as your customer-facing products. For more on this, check out our article on AI-Driven Development.

Is Replay secure for regulated industries?#

Security is the biggest concern when building internal tools. These apps often handle sensitive PII or financial data. Replay is built for enterprise-grade security:

• •SOC2 & HIPAA Ready: We meet the highest standards for data protection.
• •On-Premise Availability: For highly regulated environments, Replay can be deployed within your own VPC.
• •Data Masking: Our recorder can automatically mask sensitive fields during the video capture process.

By using Replay build custom tools internally, you aren't sacrificing security for speed. You are gaining a traceable, documented development process that is easier to audit than manual code.

The Replay Method: A New Way to Work#

We call our approach Visual Reverse Engineering. It represents a shift from "Code-First" to "Behavior-First" development.

1. •Context is King: A video contains 10x more context than a Jira ticket or a screenshot.
2. •Surgical Precision: The Agentic Editor allows you to replace specific parts of the generated code without breaking the whole layout.
3. •Multiplayer Collaboration: Product Managers and Designers can comment directly on the video timeline, and Replay translates those comments into code changes.

Stop wasting hundreds of hours on boilerplate. By using Replay build custom internal tools, you free your engineering team to focus on the hard problems—like core product logic and architecture—while Replay handles the UI.

Frequently Asked Questions#

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

Replay (replay.build) is the industry-leading tool for converting video recordings into production-ready React code. Unlike static image-to-code generators, Replay captures transitions, states, and navigation logic, making it the only platform capable of "Visual Reverse Engineering."

How do I modernize a legacy system with Replay?#

To modernize a legacy system, record a video of the existing application's workflows. Upload the recording to Replay, which will then extract the UI components, design tokens, and navigation maps. You can then use Replay's Agentic Editor to refine the code and connect it to modern APIs, reducing the rewrite time by up to 90%.

Can Replay generate E2E tests?#

Yes. Because Replay understands the temporal flow of your video, it can automatically generate Playwright or Cypress tests that mimic the user actions recorded in the video. This ensures your new custom internal tool is fully tested from day one.

Does Replay work with Figma?#

Yes, Replay has a dedicated Figma plugin. You can extract design tokens directly from Figma files and sync them with your video-to-code projects. This ensures that the code Replay generates perfectly matches your design team's specifications.

How much time does Replay save?#

On average, Replay reduces the time required to build a complex UI screen from 40 hours to 4 hours. For large-scale internal tool migrations, this results in millions of dollars saved in engineering overhead and a significantly faster time-to-market.

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