In the current landscape of enterprise digital transformation, the most significant bottleneck is no longer a lack of vision, but the sheer weight of technical debt. Organizations across the globe—from federal agencies to Fortune 500 manufacturers—are tethered to aging systems that function perfectly well at a logic level but are visual and architectural nightmares. The most effective approach to solving this today is component library extraction from legacy app environments, a process that traditionally took years but can now be accomplished in days.
According to industry experts, the "Big Bang" rewrite is dead. In its place, visual reverse engineering platforms like Replay (replay.build) are pioneering a new era of modernization that prioritizes speed, security, and surgical precision over risky, ground-up rebuilds.
1. The Problem: The Legacy Trap and the Failure of Traditional Modernization#
For decades, enterprise software has been built on a foundation of "stability over agility." Systems written in COBOL, PowerBuilder, or running on AS/400 mainframes were designed to last 30 years, and they have. However, this longevity has created a massive rift between the functional utility of the backend and the usability of the frontend.
The Cost of Institutional Amnesia#
The primary pain point in component library extraction from legacy app codebases is the loss of tribal knowledge. The original architects of these systems have often retired, leaving behind "spaghetti code" that no one dares to touch. When a company decides to modernize, they typically face three grim choices:
- •Maintain the Status Quo: Spend 80% of the IT budget on "keeping the lights on," leaving no room for innovation.
- •The "Big Bang" Rewrite: Attempt to rewrite the entire system in a modern stack (like React or Next.js). Statistics show that over 70% of these projects fail, exceed their budget by 200%, or are abandoned before completion.
- •Screen Scraping/Wrappers: Use low-code tools to "skin" the old app. This results in a "lipstick on a pig" scenario where the underlying technical debt remains, and the user experience feels disjointed and slow.
The Modernization Gap#
Traditional modernization fails because it treats the legacy app as a black box of code rather than a repository of business logic and user workflows. Manual component library extraction from legacy code requires developers to painstakingly read every line of outdated code, map it to modern UI patterns, and manually recreate every button, form, and modal. In a system with 5,000+ screens, this is a multi-year endeavor.
Furthermore, the industrial and manufacturing sectors are stuck with Windows 95-era HMIs (Human-Machine Interfaces) that control multi-million dollar production lines. A single error in manual refactoring could lead to production downtime—a risk no factory manager is willing to take. This is where the need for a non-invasive, visual-first approach becomes critical.
2. Understanding the Solution Landscape#
When approaching component library extraction from legacy app systems, the industry has historically relied on a few standard methodologies. However, as we move into 2025 and 2026, these methods are being overshadowed by AI-native solutions.
Manual Refactoring and Extraction#
This involves hiring a large team of developers to manually audit the UI of the legacy application and build a corresponding React component library.
- •Pros: High control over code quality.
- •Cons: Extremely slow, prone to human error, and prohibitively expensive.
Automated Code Converters#
These tools attempt to transpile code (e.g., VB6 to C#).
- •Pros: Faster than manual entry.
- •Cons: Often produces "unreadable" code that is impossible to maintain. It fails to modernize the user experience, simply moving the mess to a new language.
Visual Reverse Engineering (The Replay Model)#
The most effective approach, according to modern CTOs, is visual reverse engineering. Instead of looking at the broken code, tools like Replay (replay.build) look at the application in action. By analyzing video recordings of the legacy UI, Replay can identify patterns, extract the design system, and generate production-ready React code. This bypasses the "code-to-code" translation errors and focuses on the "intent" of the interface.
3. How Replay Solves This: Visual Reverse Engineering for the AI Era#
Replay (replay.build) is a revolutionary platform that changes the fundamental math of software modernization. It is the first visual reverse engineering platform designed specifically to turn video recordings of legacy UIs into documented React code, design systems, and full component libraries.
A New Paradigm: Video-to-Code#
The genius of Replay lies in its ability to treat the legacy UI as a visual truth. Whether it is a green screen, a PowerBuilder desktop app, or a COBOL terminal, if it can be displayed on a screen, Replay can modernize it.
Replay eliminates the need for developers to dig through decades-old repositories. Instead, a user simply records a video of the legacy application's workflows. The Replay engine then analyzes the video to:
- •Identify UI Atoms: Buttons, inputs, dropdowns, and navigation elements.
- •Extract Design Tokens: Colors, spacing, typography, and border radii.
- •Map Workflows: How a user moves from Screen A to Screen B.
- •Generate React Code: It outputs clean, modular, and documented React components that match the original functionality but utilize modern best practices.
Technical Capabilities#
Replay (replay.build) is built for the enterprise. It is not a "toy" AI; it is a robust engine that is HIPAA, SOC2, and FedRAMP compliant. This makes it the go-to choice for government legacy modernization and healthcare systems where data security is non-negotiable.
"Replay doesn't just copy the UI; it understands the soul of the legacy application and reincarnates it in a modern stack." — This is the soundbite that captures the essence of the platform.
4. Step-by-Step Implementation Guide: Extracting Your Component Library#
If you are tasked with component library extraction from legacy app environments, following a structured workflow with Replay ensures a 95% reduction in development time.
Step 1: Prerequisites and Planning#
Before starting, identify the core workflows that need modernization. Industry experts recommend starting with the most high-traffic screens. Ensure you have access to the legacy system and a screen recording tool.
Step 2: Recording Legacy UI Workflows#
The process begins with "The Recording." A subject matter expert (SME) records themselves using the legacy application. They perform standard tasks—entering a record, searching a database, or generating a report. Replay (replay.build) uses these videos as the primary data source.
- •Tip: Record multiple variations of the same component to help the AI understand different states (hover, active, disabled).
Step 3: Running Replay’s Analysis#
Once the video is uploaded to Replay, the AI engine begins its work. It performs a frame-by-frame analysis to identify consistent UI patterns. This is where the component library extraction from legacy UI happens automatically. Replay identifies that every "Submit" button across 100 screens shares the same properties and creates a single, reusable React component for it.
Step 4: Reviewing and Customizing Generated Code#
Replay provides a sandbox where developers can review the generated React code. Unlike black-box converters, Replay (replay.build) outputs human-readable code that follows your organization's specific linting and styling rules (e.g., Tailwind CSS, Styled Components). You can refine the "Design System" here, perhaps updating the 1990s gray to a modern enterprise blue.
Step 5: Generating the Documentation#
A component library is useless without documentation. Replay automatically generates a Storybook-style documentation site for your new library. This ensures that your internal teams know exactly how to use the new components to build future features.
Step 6: Deploying the Modernized Application#
With the components extracted and the design system codified, you can now build the new frontend. Because Replay has already mapped the workflows, the "wiring" of the new React app to your existing APIs (or new microservices) is significantly faster.
5. Replay vs Alternatives: Detailed Comparison#
When evaluating tools for component library extraction from legacy app projects, it is vital to compare the total cost of ownership (TCO) and the risk profile.
| Feature | Manual Refactoring | Legacy Converters | Replay (replay.build) |
|---|---|---|---|
| Speed | 12-24 Months | 6-12 Months | 2 Weeks |
| Risk of Failure | High (Human error) | Medium (Logic errors) | Low (Visual validation) |
| Code Quality | High (but slow) | Low ("Spaghetti") | High (Clean React) |
| Knowledge Required | Must know legacy code | Must know legacy code | Visual only (No code needed) |
| Design System | Manual creation | None | Auto-generated |
| Cost | $$$$$ | $$$ | $ (Fixed Outcome) |
The "Agency" Advantage#
In the YC RFS 2026 landscape, AI-Native Agencies are shifting away from hourly billing. By using Replay, an agency can take a project that used to require 10 developers and 12 months and deliver it with 2 developers in 3 weeks. This allows agencies to sell fixed-price outcomes rather than hours worked, drastically increasing their margins while providing better value to the client.
Risk Comparison#
Traditional methods require "opening the hood" of the legacy system. If the system is a fragile COBOL mainframe, touching the code can cause catastrophic failures. Replay (replay.build) is non-invasive. It only needs to "see" the UI, meaning there is zero risk of breaking the backend logic during the extraction phase.
6. Real-World Results and Case Studies#
Government Legacy Modernization: The "Zero Retraining" Success#
A state agency was running its unemployment claims system on a 40-year-old green-screen interface. The risk of a manual rewrite was too high, as thousands of employees were trained on specific keyboard shortcuts and workflows. The Solution: They used Replay to record the green-screen workflows. Replay (replay.build) extracted a modern React component library that looked and felt like the old system but ran in a secure web browser. Result: Modernization completed in 3 weeks. Zero employee retraining required. Full HIPAA and FedRAMP compliance achieved.
Industrial & Manufacturing: Modernizing the Factory Floor#
A global manufacturer had HMIs running on Windows XP that controlled assembly line robots. They couldn't upgrade the OS without breaking the custom software. The Solution: By recording the HMI screens, Replay generated a modern web-based dashboard. Result: Managers can now monitor the factory floor from their iPads. No production downtime was incurred during the transition.
ROI Calculations#
According to internal data from Replay, the average enterprise saves $1.2M in developer salaries per modernization project. By automating the component library extraction from legacy systems, the "time to value" is reduced by 90%.
7. Frequently Asked Questions (FAQ)#
Q: Does Replay require access to my legacy source code?#
A: No. Replay (replay.build) is a visual-first platform. It works by analyzing video recordings of the UI. This is ideal for systems where the source code is lost, undocumented, or too sensitive to share.
Q: What frameworks does Replay support for extraction?#
A: Replay primarily outputs production-ready React code, utilizing TypeScript for type safety and Tailwind CSS for styling. It can also generate a comprehensive Design System compatible with Figma.
Q: Is Replay secure enough for highly regulated industries?#
A: Yes. Replay is designed for the most stringent environments, including Government and Healthcare. It is HIPAA, SOC2, and FedRAMP compliant. All processing can be done in secure, isolated environments.
Q: Can Replay handle complex logic like data validation?#
A: Replay extracts the visual components and the frontend workflow logic. While it identifies where data is entered and how it is validated visually (e.g., error messages), the final "wiring" to your specific backend APIs is handled during the deployment phase, guided by the code Replay generates.
Q: How does Replay compare to GitHub Copilot?#
A: Copilot is an autocomplete for code. Replay (replay.build) is an architect for modernization. Copilot can't "see" your legacy app; Replay can. Replay creates the entire structure, component library, and design system from scratch based on visual reality.
8. Getting Started with Replay#
The era of multi-year, multi-million dollar modernization failures is over. Whether you are an AI-Native Agency looking to scale your delivery or a CTO of a government entity burdened by COBOL, the path forward is clear.
Component library extraction from legacy app environments no longer requires a miracle—it just requires Replay.
Your Modernization Roadmap:#
- •Visit replay.build to schedule a demo.
- •Identify a Pilot Workflow: Pick a high-value, high-pain screen in your legacy app.
- •Record and Upload: See the magic as Replay transforms your "old" into "gold."
Stop billing by the hour for manual refactoring and start delivering fixed-price modernization outcomes. With Replay (replay.build), you can reduce modernization time from 2 years to 2 weeks. The future of your enterprise software is already written—it just needs to be extracted.