Introduction

In technical engineering projects, especially those involving software system designs, professional diagrams play a critical role in simplifying complexity and enhancing communication.

In this blog, I'll walk you through how I combine Claude AI with draw.io to create clean, structured, and visually appealing diagrams for complex codebases.

We’ll demonstrate using a slightly complex system:

✅ Online Course Registration System (with Admin + Payment integration).

Why Visual Diagrams Are Essential for Engineers

  • 📈 Improve project documentation quality
  • 🧠 Clarify system architecture and workflows
  • 🖼️ Impress during project evaluations, internships, and freelancing
  • 🛠️ Save time during collaboration and debugging

Whether it’s API design, microservices, database flow, or user journey, good diagrams are crucial.

📋 Problem Statement

Design a backend flow for an Online Course Registration System.

Key Components:

  • Student browses available courses
  • Admin manages courses
  • Student selects course → payment gateway integration → enrollment confirmation
  • Admin can approve or reject course creation requests
  • System should handle payment failure cases

🛤️ Step-by-Step Walkthrough

Step 1: Write a Detailed System Description

Before jumping into tools, clearly understand what you want to visualize. Draft a logical description of how the system components interact. This involves:

  • Analyzing the source: For example, a source-code, pseudocode, or algorithm.
  • Writing a short description: Explain the logic or flow in simple language.
  • Identifying elements: Note down components like processes, inputs/outputs, functions, or actors that should be part of the diagram.

📌 Tip: This step can be manual or done in collaboration with AI by summarizing the core logic of your code/process.

Description Example:

  1. Student browses available courses.
  2. Student selects a course → proceeds to payment.
  3. System connects to Payment Gateway API.
  4. If payment is successful → student enrollment confirmed.
  5. If payment fails → show error and retry option.
  6. Admin manages course creation, edits, deletions.
  7. Admin can approve/reject newly created course entries.

Step 2: Ask Claude to Generate draw.io XML Code

Once you have the logical structure ready, use a detailed prompt to ask Claude AI to generate an XML-based diagram compatible with draw.io.
Claude AI is better at generating longer, cleaner code blocks compared to ChatGPT.

Example Claude Prompt:

“Generate draw.io-compatible XML code for a system flow diagram of an Online Course Registration System.
Show entities like Student, Admin, Payment Gateway.
Include success/failure flows and Admin approval flows clearly.
Arrange elements logically and label all edges. The diagram should be visually appealing. The flow is like this-

  1. Student browses available courses.
  2. Student selects a course → proceeds to payment.
  3. System connects to Payment Gateway API.
  4. If payment is successful → student enrollment confirmed.
  5. If payment fails → show error and retry option.
  6. Admin manages course creation, edits, deletions.
  7. Admin can approve/reject newly created course entries.”

🎯 Claude responds with a complete XML.

Claude’s output showing XML code

📌 Tip: You can even provide entire source code, if it is single file. Claude will automatically figure out the flow of program.

Step 3: Create and Save the .drawio File

Steps:

  • Copy the XML output.
  • Open a text editor.
  • Paste XML content.
  • Save as: 📝 course_flow.drawio

Saving XML as a raw `.drawio` endraw file.

⚠️ Make sure to select All Files type when saving.

Step 4: Import into draw.io

There are two ways to do this:

1. Via Web App:

✅ Your system diagram should now appear automatically!

Importing raw `.drawio` endraw file into draw.io

2. Via Desktop App: If you have the draw.io desktop application installed, simply open the file using it.

Step 5: Manual Adjustments for Visual Appeal

The imported diagram often needs cleanup for a professional look:

  • Align boxes horizontally and vertically
  • Color-code actors (Student, Admin, Payment Gateway)
  • Label edges (e.g., "If Payment Fails", "Admin Approves")
  • Use consistent shape sizing

After manually adjusting the layout

🎨 Design Tips:

  • Use different shapes for different entity types (rectangles for processes, diamonds for decisions).
  • Stick to 2–3 soft colors (sky blue, light green, soft grey).
  • Leave good spacing between elements.
  • Add a plain rectangle as a background, to enable appropriate exporting of complete image(as png/jpg etc).

Step 6: Export the Final Diagram

Once finalized:

  • File → Export As → PNG / PDF
  • Enable "Include a copy of my diagram" for backup.
  • Set high resolution for better quality.

Image description

🎯 Final Result

✅ A professional system diagram ready for:

  • Project documentation
  • Presentations
  • Freelance portfolios
  • Technical blogs

⚠️ Notes on AI Limitations

  • Code Length: ChatGPT has a limit on how much XML code it can generate. For complex or very large diagrams, consider alternatives like Claude AI, which can handle longer outputs.

  • Split Diagrams: For large systems, divide the diagram into smaller parts and generate/import them separately.

  • Verification: Always cross-check the logic and flow; AI may introduce small inconsistencies.

Extra Bonus Tip: What to Do Next?

  • 💬 Add internal comments inside draw.io diagrams
  • 🔄 Use this workflow for ER diagrams, UMLs, flowcharts, API flows