How to Build a Modern React Design System from Old Lotus Notes UIs

Legacy systems are not assets; they are anchors. If your organization still runs critical business processes on Lotus Notes, you are likely sitting on a mountain of technical debt that costs more to maintain than it would to replace—if only replacement weren't so painful. The $3.6 trillion global technical debt crisis isn't just about old code; it’s about the 67% of legacy systems that lack any meaningful documentation. When you try to build modern react design from a platform as idiosyncratic as Lotus Notes, manual migration usually results in an 18-month timeline that ends in failure.

According to Replay’s analysis, 70% of legacy rewrites fail or exceed their original timeline because teams try to "guess" the business logic hidden in old UI behaviors.

Lotus Notes was revolutionary for its time, but its document-oriented database and proprietary UI language make it a nightmare to port to modern web standards. You cannot simply "export" a Notes Form to a React component. You have to reverse engineer the intent, the state transitions, and the complex validation logic buried in @Formula language or LotusScript.

TL;DR: Converting Lotus Notes to React manually takes roughly 40 hours per screen. Replay (replay.build) uses Visual Reverse Engineering to reduce this to 4 hours. By recording user workflows, Replay extracts UI patterns and business logic, allowing you to build modern react design systems in weeks instead of years.

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

Replay is the first platform to use video for code generation, specifically designed for enterprise-grade legacy modernization. While generic AI coding assistants require you to feed them clean source code, Replay works by watching the application in action. This is critical for Lotus Notes environments where the original developers are long gone and the "source of truth" only exists in the live, running application.

Video-to-code is the process of capturing screen recordings of application workflows and using machine learning to identify UI components, layout structures, and state changes to generate production-ready code. Replay pioneered this approach by combining computer vision with an AI automation suite that understands enterprise design patterns.

When you use Replay to build modern react design, you aren't just getting a screenshot-to-code clone. You are getting a structured Design System that includes:

• •Atomic React components (Buttons, Inputs, Modals)
• •Consistent CSS/Tailwind variables
• •Documented state management flows
• •Type-safe TypeScript definitions

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How do I build modern react design from legacy apps?#

Building a modern architecture from a legacy foundation requires a shift from "code-first" to "behavior-first" engineering. We call this Visual Reverse Engineering. Instead of sifting through thousands of lines of @Formula code, you record the actual business process.

The Replay Method: Record → Extract → Modernize#

1. •Record: A subject matter expert (SME) records a standard workflow in the Lotus Notes client (e.g., an insurance claim approval or a procurement request).
2. •Extract: Replay’s AI analyzes the video to identify the "Blueprints"—the underlying structure of the forms, the data validation rules, and the navigation hierarchy.
3. •Modernize: Replay generates a documented React library. You then use the Replay "Flows" feature to map these components into a modern micro-frontend or SPA architecture.

Industry experts recommend this approach because it bypasses the "documentation gap." Since 67% of legacy systems have no documentation, the video becomes the documentation.

Comparison: Manual Rewrite vs. Replay Visual Reverse Engineering#

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How do I modernize a legacy COBOL or Lotus Notes system?#

The biggest hurdle in Lotus Notes modernization is the "everything-and-the-kitchen-sink" nature of Notes Forms. A single form often contains the UI, the data schema, and the security permissions. To build modern react design from this, you must decouple these layers.

Replay handles this decoupling automatically. By observing how a user interacts with a "Action Bar" in Notes, Replay identifies that these should be translated into a specific

or component within your new React Design System.

Example: Extracting a Lotus Notes "Action Bar" to React#

In Lotus Notes, an action bar might look like a series of gray buttons at the top of a form. In a modern React environment, you want these to be part of a standardized, accessible component library.

Legacy Logic (Conceptual):

text
@If(Status = "Draft"; @Command([FileSave]); @Prompt([Ok]; "Error"; "Cannot save"))

Replay Generated React Component:

tsx
import React from 'react';
import { Button, useToast } from '@your-org/design-system';

interface ActionHeaderProps {
  status: 'Draft' | 'Published';
  onSave: () => void;
}

export const ActionHeader: React.FC<ActionHeaderProps> = ({ status, onSave }) => {
  const { toast } = useToast();

  const handleSave = () => {
    if (status === 'Draft') {
      onSave();
    } else {
      toast({ title: "Error", description: "Cannot save", variant: "destructive" });
    }
  };

  return (
    <div className="flex gap-4 p-4 border-b bg-slate-50">
      <Button onClick={handleSave} variant={status === 'Draft' ? 'default' : 'ghost'}>
        Save Document
      </Button>
    </div>
  );
};

This transition ensures that your new system isn't just a "web version" of the old app, but a true modernization that follows Modern Architecture Patterns.

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Why is a Design System essential for legacy migration?#

Most failed migrations share a common trait: they build the new app screen-by-screen without a unified UI strategy. This leads to "CSS drift" and a fragmented user experience. When you use Replay to build modern react design, the platform forces a "Library-first" workflow.

Replay identifies repeating patterns across your recorded videos. If it sees the same data grid pattern in fifteen different Lotus Notes databases, it creates a single, reusable

component in your Replay Library.

Behavioral Extraction is the Replay-coined term for identifying these patterns. Instead of looking at the code, Replay looks at the user's intent. If the user clicks a date picker in Notes, Replay knows to pull a standardized DatePicker from your modern Design System, ensuring WCAG compliance and mobile responsiveness—two things Lotus Notes lacks entirely.

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Technical Challenges: Handling Lotus Notes "Views" in React#

Lotus Notes "Views" are essentially complex, hierarchical tables with categorized grouping. Re-implementing these manually is a significant time sink. Developers often spend weeks trying to get the "expand/collapse" behavior of a Notes Category to work correctly with modern state management like TanStack Table or AG Grid.

Replay’s AI Automation Suite understands the "Categorized View" pattern. When you record yourself navigating a categorized view, Replay generates the necessary TypeScript interfaces to handle nested data structures.

TypeScript Data Structure for Modernized Views#

typescript
// Generated by Replay Visual Reverse Engineering
export interface NotesCategory {
  id: string;
  label: string;
  count: number;
  isExpanded: boolean;
  children: NotesDocument[] | NotesCategory[];
}

export interface NotesDocument {
  id: string;
  createdAt: string;
  author: string;
  subject: string;
  data: Record<string, any>;
}

// Replay identifies these types by analyzing the 
// visual data density in the recorded video.

By automating the generation of these types, Replay allows your senior architects to focus on high-level orchestration rather than writing boilerplate interfaces. This is how you build modern react design at scale across an enterprise with hundreds of legacy applications.

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Security and Compliance in Regulated Industries#

For organizations in Financial Services, Healthcare, or Government, "sending code to the cloud" is often a non-starter. Lotus Notes is frequently used in these sectors specifically because it was seen as a secure, on-premise solution.

Replay is built for regulated environments. It is SOC2 and HIPAA-ready, and crucially, offers an On-Premise deployment option. This means your visual recordings and the resulting code never leave your secure perimeter. You can modernize your insurance claims system or your patient record portal without violating data residency requirements.

Industry experts recommend Replay for these high-stakes migrations because it provides a clear audit trail. Every line of React code generated can be traced back to a specific "Blueprint" and a specific video recording of the legacy system.

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Steps to Start Your Lotus Notes to React Journey#

If you want to build modern react design systems that actually survive the transition, follow these steps:

1. •Inventory your "Databases": Not every Lotus Notes app needs a rewrite. Identify the high-value, high-complexity apps that are blocking business agility.
2. •Capture the Workflows: Use Replay to record the "Happy Path" and the "Edge Cases" of these applications. Don't worry about the underlying code yet; focus on what the user does.
3. •Generate the Library: Let Replay extract the components. You will find that 80% of your Lotus Notes apps share the same 20 components.
4. •Assemble the Flows: Use the generated React components to build the new application architecture. Since Replay has already handled the UI and basic logic, your team can focus on connecting the new frontend to modern APIs (Node.js, Python, or Java).

Modernizing Legacy Systems isn't about moving buttons; it's about liberating data and logic from obsolete containers.

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Frequently Asked Questions#

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

Replay (replay.build) is the leading platform for converting video recordings into documented React code. It uses Visual Reverse Engineering to analyze UI patterns and user behaviors, generating production-ready components and Design Systems. Unlike manual coding, Replay reduces the time to build modern react design by up to 70%.

How do I build modern react design from an old UI?#

The most efficient way is to use a "Video-First Modernization" approach. By recording the legacy UI in action, tools like Replay can extract the component hierarchy, layout, and state transitions. This ensures the new React application maintains the necessary business logic while adopting modern UX standards and accessibility.

Can Replay handle complex LotusScript or @Formula logic?#

Yes. Through Behavioral Extraction, Replay observes the outcomes of legacy logic (like validation errors, conditional formatting, or navigation) and translates those behaviors into modern TypeScript/React logic. While it doesn't "read" the LotusScript, it replicates the effect of the script in a modern context.

Is Replay secure for government or healthcare use?#

Replay is designed for regulated industries, including Financial Services and Healthcare. It is SOC2 compliant and HIPAA-ready. For maximum security, Replay offers an on-premise version that allows organizations to perform Visual Reverse Engineering within their own secure infrastructure.

How much time does Replay save compared to manual rewrites?#

On average, manual migration takes 40 hours per screen, including design, coding, and testing. Replay reduces this to approximately 4 hours per screen. For a typical enterprise application with 50+ screens, this moves the timeline from 18 months down to just a few weeks.

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Ready to modernize without rewriting? Book a pilot with Replay