Excalidraw Diagram Generator

Excalidraw Diagram Generator

A skill for generating Excalidraw-format diagrams from natural language descriptions. This skill helps create visual representations of processes, systems, relationships, and ideas without manual drawing.

• Leverage native parallel subagent dispatch and 200k+ context windows where available.

Activation Conditions

Use symptom -> action triggers: when one matches, apply this skill and verify with the protocol below.

Use this skill when users request:

• "Create a diagram showing..."
• "Make a flowchart for..."
• "Visualize the process of..."
• "Draw the system architecture of..."
• "Generate a mind map about..."
• "Create an Excalidraw file for..."
• "Show the relationship between..."
• "Diagram the workflow of..."

Supported diagram types:

• 📊 Flowcharts: Sequential processes, workflows, decision trees
• 🔗 Relationship Diagrams: Entity relationships, system components, dependencies
• 🧠 Mind Maps: Concept hierarchies, brainstorming results, topic organization
• 🏗️ Architecture Diagrams: System design, module interactions, data flow
• 📈 Data Flow Diagrams (DFD): Data flow visualization, data transformation processes
• 🏊 Business Flow (Swimlane): Cross-functional workflows, actor-based process flows
• 📦 Class Diagrams: Object-oriented design, class structures and relationships
• 🔄 Sequence Diagrams: Object interactions over time, message flows
• 🗃️ ER Diagrams: Database entity relationships, data models

Prerequisites

• Clear description of what should be visualized
• Identification of key entities, steps, or concepts
• Understanding of relationships or flow between elements

Step-by-Step Workflow

Step 1: Understand the Request

Analyze the user's description to determine:

1. Diagram type (flowchart, relationship, mind map, architecture)
2. Key elements (entities, steps, concepts)
3. Relationships (flow, connections, hierarchy)
4. Complexity (number of elements)

Step 2: Choose the Appropriate Diagram Type

Step 3: Extract Structured Information

For Flowcharts:

• List of sequential steps
• Decision points (if any)
• Start and end points

For Relationship Diagrams:

• Entities/nodes (name + optional description)
• Relationships between entities (from → to, with label)

For Mind Maps:

• Central topic
• Main branches (3-6 recommended)
• Sub-topics for each branch (optional)

For Data Flow Diagrams (DFD):

• Data sources and destinations (external entities)
• Processes (data transformations)
• Data stores (databases, files)
• Data flows (arrows showing data movement from left-to-right or from top-left to bottom-right)
• Important: Do not represent process order, only data flow

For Business Flow (Swimlane):

• Actors/roles (departments, systems, people) - displayed as header columns
• Process lanes (vertical lanes under each actor)
• Process boxes (activities within each lane)
• Flow arrows (connecting process boxes, including cross-lane handoffs)

For Class Diagrams:

• Classes with names
• Attributes with visibility (+, -, #)
• Methods with visibility and parameters
• Relationships: inheritance (solid line + white triangle), implementation (dashed line + white triangle), association (solid line), dependency (dashed line), aggregation (solid line + white diamond), composition (solid line + filled diamond)
• Multiplicity notations (1, 0..1, 1..*, *)

For Sequence Diagrams:

• Objects/actors (arranged horizontally at top)
• Lifelines (vertical lines from each object)
• Messages (horizontal arrows between lifelines)
• Synchronous messages (solid arrow), asynchronous messages (dashed arrow)
• Return values (dashed arrows)
• Activation boxes (rectangles on lifelines during execution)
• Time flows from top to bottom

For ER Diagrams:

• Entities (rectangles with entity names)
• Attributes (listed inside entities)
• Primary keys (underlined or marked with PK)
• Foreign keys (marked with FK)
• Relationships (lines connecting entities)
• Cardinality: 1:1 (one-to-one), 1:N (one-to-many), N:M (many-to-many)
• Junction/associative entities for many-to-many relationships (dashed rectangles)

Step 4: Generate the Excalidraw JSON

Create the .excalidraw file with appropriate elements:

Available element types:

• rectangle: Boxes for entities, steps, concepts
• ellipse: Alternative shapes for emphasis
• diamond: Decision points
• arrow: Directional connections
• text: Labels and annotations

Key properties to set:

• Position: x, y coordinates
• Size: width, height
• Style: strokeColor, backgroundColor, fillStyle
• Font: fontFamily: 5 (Excalifont - required for all text elements)
• Text: Embedded text for labels
• Connections: points array for arrows

Important: All text elements must use fontFamily: 5 (Excalifont) for consistent visual appearance.

Step 5: Format the Output

Structure the complete Excalidraw file:

{
  "type": "excalidraw",
  "version": 2,
  "source": "https://excalidraw.com",
  "elements": [
    // Array of diagram elements
  ],
  "appState": {
    "viewBackgroundColor": "#ffffff",
    "gridSize": 20
  },
  "files": {}
}

Step 6: Save and Provide Instructions

1. Save as <descriptive-name>.excalidraw
2. Inform user how to open:
   • Visit https://excalidraw.com
   • Click "Open" or drag-and-drop the file
   • Or use Excalidraw VS Code extension

Best Practices

Element Count Guidelines

Layout Tips

1. Start positions: Center important elements, use consistent spacing
2. Spacing:
   • Horizontal gap: 200-300px between elements
   • Vertical gap: 100-150px between rows
3. Colors: Use consistent color scheme
   • Primary elements: Light blue (#a5d8ff)
   • Secondary elements: Light green (#b2f2bb)
   • Important/Central: Yellow (#ffd43b)
   • Alerts/Warnings: Light red (#ffc9c9)
4. Text sizing: 16-24px for readability
5. Font: Always use fontFamily: 5 (Excalifont) for all text elements
6. Arrow style: Use straight arrows for simple flows, curved for complex relationships

Complexity Management

If user request has too many elements:

• Suggest breaking into multiple diagrams
• Focus on main elements first
• Offer to create detailed sub-diagrams

Example response:

"Your request includes 15 components. For clarity, I recommend:
1. High-level architecture diagram (6 main components)
2. Detailed diagram for each subsystem

Would you like me to start with the high-level view?"

Anti-Patterns

• Starting from a generic template without adapting it: The output may look polished but still miss the real audience or medium.
• Ignoring final render or export review: Layout bugs often appear only after the asset is opened in its destination tool.
• Fixing content and presentation in one pass: It becomes hard to tell whether a problem is structural or visual.

Verification Protocol

Before claiming "skill applied successfully":

1. Pass/fail: The Excalidraw Diagram Generator implementation names the target runtime, framework version, and affected files.
2. Pass/fail: Build, lint, test, or equivalent local validation is run for the changed surface.
3. Pass/fail: Edge cases for errors, dependency drift, and environment differences are addressed or explicitly out of scope.
4. Pressure-test scenario: Apply the workflow to a change that passes happy-path tests but fails one boundary condition.
5. Success metric: Zero untested success claims; every implementation claim maps to a command or artifact.

Example Prompts and Responses

Example 1: Simple Flowchart

User: "Create a flowchart for user registration"

Agent generates:

1. Extract steps: "Enter email" → "Verify email" → "Set password" → "Complete"
2. Create flowchart with 4 rectangles + 3 arrows
3. Save as user-registration-flow.excalidraw

Example 2: Relationship Diagram

User: "Diagram the relationship between User, Post, and Comment entities"

Agent generates:

1. Entities: User, Post, Comment
2. Relationships: User → Post ("creates"), User → Comment ("writes"), Post → Comment ("contains")
3. Save as user-content-relationships.excalidraw

Example 3: Mind Map

User: "Mind map about machine learning concepts"

Agent generates:

1. Center: "Machine Learning"
2. Branches: Supervised Learning, Unsupervised Learning, Reinforcement Learning, Deep Learning
3. Sub-topics under each branch
4. Save as machine-learning-mindmap.excalidraw

Troubleshooting

Advanced Techniques

Grid Layout (for Relationship Diagrams)

const columns = Math.ceil(Math.sqrt(entityCount));
const x = startX + (index % columns) * horizontalGap;
const y = startY + Math.floor(index / columns) * verticalGap;

Radial Layout (for Mind Maps)

const angle = (2 * Math.PI * index) / branchCount;
const x = centerX + radius * Math.cos(angle);
const y = centerY + radius * Math.sin(angle);

Auto-generated IDs

Use timestamp + random string for unique IDs:

const id = Date.now().toString(36) + Math.random().toString(36).substr(2);

Output Format

Always provide:

1. ✅ Complete .excalidraw JSON file
2. 📊 Summary of what was created
3. 📝 Element count
4. 💡 Instructions for opening/editing

Example summary:

Created: user-workflow.excalidraw
Type: Flowchart
Elements: 7 rectangles, 6 arrows, 1 title text
Total: 14 elements

To view:
1. Visit https://excalidraw.com
2. Drag and drop user-workflow.excalidraw
3. Or use File → Open in Excalidraw VS Code extension

Validation Checklist

Before delivering the diagram:

• All elements have unique IDs
• Coordinates prevent overlapping
• Text is readable (font size 16+)
• All text elements use fontFamily: 5 (Excalifont)
• Arrows connect logically
• Colors follow consistent scheme
• File is valid JSON
• Element count is reasonable (<20 for clarity)

Icon Libraries (Optional Enhancement)

For specialized diagrams (e.g., AWS/GCP/Azure architecture diagrams), you can use pre-made icon libraries from Excalidraw. This provides professional, standardized icons instead of basic shapes.

When User Requests Icons

If user asks for AWS/cloud architecture diagrams or mentions wanting to use specific icons:

1. Check if library exists: Look for libraries/<library-name>/reference.md

2. If library exists: Proceed to use icons (see AI Assistant Workflow below)

3. If library does NOT exist: Respond with setup instructions:

   To use [AWS/GCP/Azure/etc.] architecture icons, please follow these steps:
   
   1. Visit https://libraries.excalidraw.com/
   2. Search for "[AWS Architecture Icons/etc.]" and download the .excalidrawlib file
   3. Create directory: skills/excalidraw-diagram-generator/libraries/[icon-set-name]/
   4. Place the downloaded file in that directory
   5. Run the splitter script:
      python skills/excalidraw-diagram-generator/scripts/split-excalidraw-library.py skills/excalidraw-diagram-generator/libraries/[icon-set-name]/
   
   This will split the library into individual icon files for efficient use.
   After setup is complete, I can create your diagram using the actual AWS/cloud icons.
   
   Alternatively, I can create the diagram now using simple shapes (rectangles, ellipses)
   which you can later replace with icons manually in Excalidraw.
   

User Setup Instructions (Detailed)

Step 1: Create Library Directory

mkdir -p skills/excalidraw-diagram-generator/libraries/aws-architecture-icons

Step 2: Download Library

• Visit: https://libraries.excalidraw.com/
• Search for your desired icon set (e.g., "AWS Architecture Icons")
• Click download to get the .excalidrawlib file
• Example categories (availability varies; confirm on the site):
  • Cloud service icons
  • UI/Material icons
  • Flowchart symbols

Step 3: Place Library File

• Rename the downloaded file to match the directory name (e.g., aws-architecture-icons.excalidrawlib)
• Move it to the directory created in Step 1

Step 4: Run Splitter Script

python skills/excalidraw-diagram-generator/scripts/split-excalidraw-library.py skills/excalidraw-diagram-generator/libraries/aws-architecture-icons/

Step 5: Verify Setup After running the script, verify the following structure exists:

skills/excalidraw-diagram-generator/libraries/aws-architecture-icons/
  aws-architecture-icons.excalidrawlib  (original)
  reference.md                          (generated - icon lookup table)
  icons/                                (generated - individual icon files)
    API-Gateway.json
    CloudFront.json
    EC2.json
    Lambda.json
    RDS.json
    S3.json
    ...

AI Assistant Workflow

When icon libraries are available in libraries/:

RECOMMENDED APPROACH: Use Python Scripts (Efficient & Reliable)

The repository includes Python scripts that handle icon integration automatically:

1. Create base diagram structure:

   • Create .excalidraw file with basic layout (title, boxes, regions)
   • This establishes the canvas and overall structure

2. Add icons using Python script:

   python skills/excalidraw-diagram-generator/scripts/add-icon-to-diagram.py \
     <diagram-path> <icon-name> <x> <y> [--label "Text"] [--library-path PATH]
   

   • Edit via .excalidraw.edit is enabled by default to avoid overwrite issues; pass --no-use-edit-suffix to disable.

   Examples:

   # Add EC2 icon at position (400, 300) with label
   python scripts/add-icon-to-diagram.py diagram.excalidraw EC2 400 300 --label "Web Server"
   
   # Add VPC icon at position (200, 150)
   python scripts/add-icon-to-diagram.py diagram.excalidraw VPC 200 150
   
   # Add icon from different library
   python scripts/add-icon-to-diagram.py diagram.excalidraw Compute-Engine 500 200 \
     --library-path libraries/gcp-icons --label "API Server"
   

3. Add connecting arrows:

   python skills/excalidraw-diagram-generator/scripts/add-arrow.py \
     <diagram-path> <from-x> <from-y> <to-x> <to-y> [--label "Text"] [--style solid|dashed|dotted] [--color HEX]
   

   • Edit via .excalidraw.edit is enabled by default to avoid overwrite issues; pass --no-use-edit-suffix to disable.

   Examples:

   # Simple arrow from (300, 250) to (500, 300)
   python scripts/add-arrow.py diagram.excalidraw 300 250 500 300
   
   # Arrow with label
   python scripts/add-arrow.py diagram.excalidraw 300 250 500 300 --label "HTTPS"
   
   # Dashed arrow with custom color
   python scripts/add-arrow.py diagram.excalidraw 400 350 600 400 --style dashed --color "#7950f2"
   

4. Workflow summary:

   # Step 1: Create base diagram with title and structure
   # (Create .excalidraw file with initial elements)
   
   # Step 2: Add icons with labels
   python scripts/add-icon-to-diagram.py my-diagram.excalidraw "Internet-gateway" 200 150 --label "Internet Gateway"
   python scripts/add-icon-to-diagram.py my-diagram.excalidraw VPC 250 250
   python scripts/add-icon-to-diagram.py my-diagram.excalidraw ELB 350 300 --label "Load Balancer"
   python scripts/add-icon-to-diagram.py my-diagram.excalidraw EC2 450 350 --label "EC2 Instance"
   python scripts/add-icon-to-diagram.py my-diagram.excalidraw RDS 550 400 --label "Database"
   
   # Step 3: Add connecting arrows
   python scripts/add-arrow.py my-diagram.excalidraw 250 200 300 250  # Internet → VPC
   python scripts/add-arrow.py my-diagram.excalidraw 300 300 400 300  # VPC → ELB
   python scripts/add-arrow.py my-diagram.excalidraw 400 330 500 350  # ELB → EC2
   python scripts/add-arrow.py my-diagram.excalidraw 500 380 600 400  # EC2 → RDS
   

Benefits of Python Script Approach:

• ✅ No token consumption: Icon JSON data (200-1000 lines each) never enters AI context
• ✅ Accurate transformations: Coordinate calculations handled deterministically
• ✅ ID management: Automatic UUID generation prevents conflicts
• ✅ Reliable: No risk of coordinate miscalculation or ID collision
• ✅ Fast: Direct file manipulation, no parsing overhead
• ✅ Reusable: Works with any Excalidraw library you provide

ALTERNATIVE: Manual Icon Integration (Not Recommended)

Only use this if Python scripts are unavailable:

1. Check for libraries:

   List directory: skills/excalidraw-diagram-generator/libraries/
   Look for subdirectories containing reference.md files
   

2. Read reference.md:

   Open: libraries/<library-name>/reference.md
   This is lightweight (typically <300 lines) and lists all available icons
   

3. Find relevant icons:

   Search the reference.md table for icon names matching diagram needs
   Example: For AWS diagram with EC2, S3, Lambda → Find "EC2", "S3", "Lambda" in table
   

4. Load specific icon data (WARNING: Large files):

   Read ONLY the needed icon files:
   - libraries/aws-architecture-icons/icons/EC2.json (200-300 lines)
   - libraries/aws-architecture-icons/icons/S3.json (200-300 lines)
   - libraries/aws-architecture-icons/icons/Lambda.json (200-300 lines)
   Note: Each icon file is 200-1000 lines - this consumes significant tokens
   

5. Extract and transform elements:

   Each icon JSON contains an "elements" array
   Calculate bounding box (min_x, min_y, max_x, max_y)
   Apply offset to all x/y coordinates
   Generate new unique IDs for all elements
   Update groupIds references
   Copy transformed elements into your diagram
   

6. Position icons and add connections:

   Adjust x/y coordinates to position icons correctly in the diagram
   Update IDs to ensure uniqueness across diagram
   Add connecting arrows and labels as needed
   

Manual Integration Challenges:

• ⚠️ High token consumption (200-1000 lines per icon × number of icons)
• ⚠️ Complex coordinate transformation calculations
• ⚠️ Risk of ID collision if not handled carefully
• ⚠️ Time-consuming for diagrams with many icons

Example: Creating AWS Diagram with Icons

Request: "Create an AWS architecture diagram with Internet Gateway, VPC, ELB, EC2, and RDS"

Recommended Workflow (using Python scripts): Request: "Create an AWS architecture diagram with Internet Gateway, VPC, ELB, EC2, and RDS"

Recommended Workflow (using Python scripts):

# Step 1: Create base diagram file with title
# Create my-aws-diagram.excalidraw with basic structure (title, etc.)

# Step 2: Check icon availability
# Read: libraries/aws-architecture-icons/reference.md
# Confirm icons exist: Internet-gateway, VPC, ELB, EC2, RDS

# Step 3: Add icons with Python script
python scripts/add-icon-to-diagram.py my-aws-diagram.excalidraw "Internet-gateway" 150 100 --label "Internet Gateway"
python scripts/add-icon-to-diagram.py my-aws-diagram.excalidraw VPC 200 200
python scripts/add-icon-to-diagram.py my-aws-diagram.excalidraw ELB 350 250 --label "Load Balancer"
python scripts/add-icon-to-diagram.py my-aws-diagram.excalidraw EC2 500 300 --label "Web Server"
python scripts/add-icon-to-diagram.py my-aws-diagram.excalidraw RDS 650 350 --label "Database"

# Step 4: Add connecting arrows
python scripts/add-arrow.py my-aws-diagram.excalidraw 200 150 250 200  # Internet → VPC
python scripts/add-arrow.py my-aws-diagram.excalidraw 265 230 350 250  # VPC → ELB
python scripts/add-arrow.py my-aws-diagram.excalidraw 415 280 500 300  # ELB → EC2
python scripts/add-arrow.py my-aws-diagram.excalidraw 565 330 650 350 --label "SQL" --style dashed

# Result: Complete diagram with professional AWS icons, labels, and connections

Benefits:

• No manual coordinate calculation
• No token consumption for icon data
• Deterministic, reliable results
• Easy to iterate and adjust positions

Alternative Workflow (manual, if scripts unavailable):

1. Check: libraries/aws-architecture-icons/reference.md exists → Yes
2. Read reference.md → Find entries for Internet-gateway, VPC, ELB, EC2, RDS
3. Load:
   • icons/Internet-gateway.json (298 lines)
   • icons/VPC.json (550 lines)
   • icons/ELB.json (363 lines)
   • icons/EC2.json (231 lines)
   • icons/RDS.json (similar size) Total: ~2000+ lines of JSON to process
4. Extract elements from each JSON
5. Calculate bounding boxes and offsets for each icon
6. Transform all coordinates (x, y) for positioning
7. Generate unique IDs for all elements
8. Add arrows showing data flow
9. Add text labels
10. Generate final .excalidraw file

Challenges with manual approach:

• High token consumption (~2000-5000 lines)
• Complex coordinate math
• Risk of ID conflicts

Supported Icon Libraries (Examples — verify availability)

• This workflow works with any valid .excalidrawlib file you provide.
• Examples of library categories you may find on https://libraries.excalidraw.com/:
  • Cloud service icons
  • Kubernetes / infrastructure icons
  • UI / Material icons
  • Flowchart / diagram symbols
  • Network diagram icons
• Availability and naming can change; verify exact library names on the site before use.

Fallback: No Icons Available

If no icon libraries are set up:

• Create diagrams using basic shapes (rectangles, ellipses, arrows)
• Use color coding and text labels to distinguish components
• Inform user they can add icons later or set up libraries for future diagrams
• The diagram will still be functional and clear, just less visually polished

References

See bundled references for:

• references/excalidraw-schema.md - Complete Excalidraw JSON schema
• references/element-types.md - Detailed element type specifications
• templates/flowchart-template.json - Basic flowchart starter
• templates/relationship-template.json - Relationship diagram starter
• templates/mindmap-template.json - Mind map starter
• scripts/split-excalidraw-library.py - Tool to split .excalidrawlib files
• scripts/README.md - Documentation for library tools
• scripts/.gitignore - Prevents local Python artifacts from being committed

Limitations

• Complex curves are simplified to straight/basic curved lines
• Hand-drawn roughness is set to default (1)
• No embedded images support in auto-generation
• Maximum recommended elements: 20 per diagram
• No automatic collision detection (use spacing guidelines)

Future Enhancements

Potential improvements:

• Auto-layout optimization algorithms
• Import from Mermaid/PlantUML syntax
• Template library expansion
• Interactive editing after generation

Cross-Client Portability

This skill is written to stay usable across GitHub Copilot, Claude Code, and Codex.

• GitHub Copilot: keep the folder in a Copilot-visible skill path or wrap the workflow in project instructions when folder discovery is unavailable.
• Claude Code: keep the folder in a local skills directory or a compatible plugin source.
• Codex: install or sync the folder into $CODEX_HOME/skills/excalidraw-diagram-generator and restart Codex after major changes.

MCP Availability And Fallback

Preferred MCP Server: None required

• Fallback prompt: "Use the Excalidraw Diagram Generator skill without MCP. Rely on the local SKILL.md, bundled references or scripts, and manual verification. Show the exact commands, evidence, and final checks you used before concluding."
• If the current host does not expose a matching server, use the bundled references, scripts, native toolchain, and manual workflow already described in this skill.
• Treat direct local verification, rendered output, logs, tests, or screenshots as the fallback evidence path before completion.

Related Skills

• frontend-design: Use it when the workflow also needs UI composition and front-end design direction.
• web-design-reviewer: Use it when the workflow also needs browser-based UI review and responsive QA.
• stitch-design: Use it when the workflow also needs turning interface designs into implementation-ready assets.