Excalidraw Diagram Generator

This skill generates Excalidraw diagrams programmatically using Python. Instead of creating ASCII diagrams, use this to produce professional-looking, editable diagrams.

Output format: .excalidraw JSON files that can be:

•Opened at https://excalidraw.com (drag & drop the file)
•Edited in VS Code with the Excalidraw extension
•Embedded in documentation
•Exported to PNG for embedding in presentations, etc.

Using the bin/ Directory

Important: This skill provides all required executables in the bin/ directory. Do not rely on system PATH - always use the full path to executables.

Tool	Path
Python	`~/.ai/agent/skills/excalidraw-diagrams/bin/python`
Node.js	`~/.ai/agent/skills/excalidraw-diagrams/bin/node`
npm	`~/.ai/agent/skills/excalidraw-diagrams/bin/npm`
npx	`~/.ai/agent/skills/excalidraw-diagrams/bin/npx`

When executing scripts:

bash

# Python scripts
~/.ai/agent/skills/excalidraw-diagrams/bin/python scripts/excalidraw_generator.py

# Node.js scripts
~/.ai/agent/skills/excalidraw-diagrams/bin/node scripts/export_playwright.js

Quick Start

Method 1: Direct Python Script (Recommended)

Write a Python script using the generator library and run it:

python

#!/usr/bin/env python3
import sys
import os
sys.path.insert(0, os.path.expanduser("~/.ai/agent/skills/excalidraw-diagrams/scripts"))
from excalidraw_generator import Diagram, Flowchart, ArchitectureDiagram

# Create your diagram
d = Diagram()
box1 = d.box(100, 100, "Step 1", color="blue")
box2 = d.box(300, 100, "Step 2", color="green")
d.arrow_between(box1, box2, "next")
d.save("my_diagram.excalidraw")

Run with:

bash

bin/python /path/to/your_script.py

Method 2: Inline Python Execution

bash

bin/python -c "
import sys, os
sys.path.insert(0, os.path.expanduser('~/.ai/agent/skills/excalidraw-diagrams/scripts'))
from excalidraw_generator import Diagram

d = Diagram()
a = d.box(100, 100, 'Hello', color='blue')
b = d.box(300, 100, 'World', color='green')
d.arrow_between(a, b)
d.save('hello.excalidraw')
print('Created: hello.excalidraw')
"

API Reference

Diagram Class

The base class for all diagrams.

python

from excalidraw_generator import Diagram

d = Diagram(background="#ffffff")  # white background

Methods

box(x, y, label, width=150, height=60, color="blue", shape="rectangle", font_size=18)

Create a labeled shape. Returns an Element for connecting.

•x, y: Position (top-left corner)
•label: Text to display
•color: "blue", "green", "red", "yellow", "orange", "violet", "cyan", "teal", "gray", "black"
•shape: "rectangle", "ellipse", "diamond"

python

box1 = d.box(100, 100, "Process A", color="blue")
box2 = d.box(100, 200, "Decision?", color="yellow", shape="diamond")

text_box(x, y, content, font_size=20, color="black")

Create standalone text.

python

d.text_box(100, 50, "System Architecture", font_size=28, color="black")

arrow_between(source, target, label=None, color="black", from_side="auto", to_side="auto")

Draw an arrow between two elements.

•from_side, to_side: "auto", "left", "right", "top", "bottom"

python

d.arrow_between(box1, box2, "sends data")
d.arrow_between(box1, box3, from_side="bottom", to_side="top")

line_between(source, target, color="black")

Draw a line (no arrowhead) between elements.

save(path)

Save the diagram. Extension .excalidraw added if not present.

python

d.save("output/my_diagram")  # Creates output/my_diagram.excalidraw

Configuration & Styling

The diagram generator supports extensive customization through configuration classes.

DiagramStyle - Global Appearance

Control the overall look of all elements in the diagram:

python

from excalidraw_generator import Diagram, DiagramStyle

# Create a clean, professional diagram
d = Diagram(diagram_style=DiagramStyle(
    roughness=0,           # 0=clean, 1=hand-drawn, 2=rough sketch
    stroke_style="solid",  # "solid", "dashed", "dotted"
    stroke_width=2,        # Line thickness (1-4)
    color_scheme="corporate"  # Named color scheme
))

Roughness levels:

•0 - Architect: Clean, precise lines
•1 - Artist: Normal hand-drawn look (default)
•2 - Cartoonist: Rough, sketchy appearance

Color Schemes

Use semantic colors from predefined schemes:

python

# Available schemes: "default", "monochrome", "corporate", "vibrant", "earth"
d = Diagram(diagram_style=DiagramStyle(color_scheme="vibrant"))

# Get colors by role
primary = d.scheme_color("primary")     # Main components
secondary = d.scheme_color("secondary") # Supporting elements
accent = d.scheme_color("accent")       # Highlights
warning = d.scheme_color("warning")     # Caution states
danger = d.scheme_color("danger")       # Error states
neutral = d.scheme_color("neutral")     # Backgrounds, users

Scheme color mappings:

Scheme	Primary	Secondary	Accent	Warning	Danger
default	blue	green	violet	yellow	red
monochrome	black	gray	gray	gray	black
corporate	blue	teal	violet	orange	red
vibrant	violet	cyan	orange	yellow	red
earth	teal	green	orange	yellow	red

FlowchartStyle - Flowchart Customization

Customize flowchart node colors and routing behavior:

python

from excalidraw_generator import Flowchart, FlowchartStyle

fc = Flowchart(flowchart_style=FlowchartStyle(
    start_color="cyan",      # Start node color
    end_color="red",         # End node color
    process_color="blue",    # Process node color
    decision_color="orange", # Decision diamond color
))

ArchitectureStyle - Architecture Diagram Customization

python

from excalidraw_generator import ArchitectureDiagram, ArchitectureStyle

arch = ArchitectureDiagram(architecture_style=ArchitectureStyle(
    component_color="blue",
    database_color="green",
    service_color="violet",
    user_color="gray",
))

BoxStyle - Text Box Sizing

Control automatic text box sizing:

python

from excalidraw_generator import Diagram, BoxStyle

d = Diagram(box_style=BoxStyle(
    h_padding=40,      # Horizontal padding (total)
    v_padding=24,      # Vertical padding (total)
    min_width=80,      # Minimum box width
    min_height=40,     # Minimum box height
    font_size=18,      # Default font size
    font_family="hand" # "hand", "normal", "code"
))

Flowchart Class

Specialized for flowcharts with automatic positioning.

python

from excalidraw_generator import Flowchart

fc = Flowchart(direction="vertical", spacing=80)

fc.start("Begin")
fc.process("p1", "Process Data")
fc.decision("d1", "Valid?")
fc.process("p2", "Save")
fc.end("Done")

fc.connect("__start__", "p1")
fc.connect("p1", "d1")
fc.connect("d1", "p2", label="Yes")
fc.connect("d1", "__end__", label="No")

fc.save("flowchart.excalidraw")

Methods

•start(label="Start") - Green ellipse
•end(label="End") - Red ellipse
•process(node_id, label, color="blue") - Blue rectangle
•decision(node_id, label, color="yellow") - Yellow diamond
•node(node_id, label, shape, color, width, height) - Generic node
•connect(from_id, to_id, label=None) - Arrow between nodes
•position_at(x, y) - Set position for next node

AutoLayoutFlowchart Class

For complex flowcharts with automatic hierarchical layout. Requires grandalf package.

python

from excalidraw_generator import AutoLayoutFlowchart, DiagramStyle, FlowchartStyle, LayoutConfig

fc = AutoLayoutFlowchart(
    diagram_style=DiagramStyle(roughness=0),  # Clean lines
    flowchart_style=FlowchartStyle(decision_color="orange"),
    layout_config=LayoutConfig(
        vertical_spacing=100,
        horizontal_spacing=80,
    )
)

# Add nodes with semantic types
fc.add_node("start", "Start", shape="ellipse", color="green", node_type="terminal")
fc.add_node("process1", "Validate Input", node_type="process")
fc.add_node("check", "Is Valid?", shape="diamond", color="yellow", node_type="decision")
fc.add_node("success", "Process Data", node_type="process")
fc.add_node("error", "Show Error", color="red", node_type="process")
fc.add_node("end", "End", shape="ellipse", color="red", node_type="terminal")

# Add edges (arrows)
fc.add_edge("start", "process1")
fc.add_edge("process1", "check")
fc.add_edge("check", "success", label="Yes")
fc.add_edge("check", "error", label="No")
fc.add_edge("success", "end")
fc.add_edge("error", "process1", label="Retry")  # Back-edge auto-routes through whitespace

# Compute layout and render
result = fc.compute_layout(
    two_column=True,           # Split tall diagrams into columns
    target_aspect_ratio=0.8,   # Target width/height ratio
)

fc.save("auto_flowchart.excalidraw")

Node types for routing:

•terminal - Start/end nodes
•process - Standard processing steps
•decision - Decision diamonds (arrows exit from sides)

Methods

•add_node(node_id, label, shape, color, width, height, node_type) - Add a node
•add_edge(from_id, to_id, label, color) - Add an edge
•compute_layout(start_x, start_y, max_width, max_height, routing, two_column, target_aspect_ratio, column_gap) - Auto-position nodes

ArchitectureDiagram Class

For system architecture diagrams.

python

from excalidraw_generator import ArchitectureDiagram

arch = ArchitectureDiagram()

# Add components at specific positions
arch.user("user", "User", x=100, y=200)
arch.component("frontend", "React App", x=250, y=200, color="blue")
arch.service("api", "API Gateway", x=450, y=200, color="violet")
arch.database("db", "PostgreSQL", x=650, y=200, color="green")

# Connect them
arch.connect("user", "frontend", "HTTPS")
arch.connect("frontend", "api", "REST")
arch.connect("api", "db", "SQL")

arch.save("architecture.excalidraw")

Methods

•component(id, label, x, y, width=150, height=80, color="blue")
•database(id, label, x, y, color="green") - Ellipse shape
•service(id, label, x, y, color="violet")
•user(id, label="User", x=100, y=100) - Gray ellipse
•connect(from_id, to_id, label=None, bidirectional=False)

Color Reference

Available colors (stroke color, with matching light background):

Color	Stroke Hex	Use For
`blue`	#1971c2	Primary components
`green`	#2f9e44	Success, databases
`red`	#e03131	Errors, end states
`yellow`	#f08c00	Warnings, decisions
`orange`	#e8590c	Highlights
`violet`	#6741d9	Services
`cyan`	#0c8599	Network
`teal`	#099268	Secondary
`gray`	#868e96	Users, actors
`black`	#1e1e1e	Text, arrows

Complete Examples

Example 1: Simple Flow

python

import sys, os
sys.path.insert(0, os.path.expanduser("~/.ai/agent/skills/excalidraw-diagrams/scripts"))
from excalidraw_generator import Diagram

d = Diagram()

# Title
d.text_box(200, 30, "Data Processing Pipeline", font_size=24)

# Boxes
input_box = d.box(100, 100, "Input", color="gray")
process = d.box(300, 100, "Process", color="blue")
output = d.box(500, 100, "Output", color="green")

# Arrows
d.arrow_between(input_box, process, "raw data")
d.arrow_between(process, output, "results")

d.save("pipeline.excalidraw")

Example 2: Decision Flowchart

python

import sys, os
sys.path.insert(0, os.path.expanduser("~/.ai/agent/skills/excalidraw-diagrams/scripts"))
from excalidraw_generator import Flowchart

fc = Flowchart(direction="vertical", spacing=100)

fc.start("User Request")
fc.process("auth", "Authenticate")
fc.decision("valid", "Valid Token?")

# Branch for Yes
fc.position_at(300, 340)
fc.process("proc", "Process Request")
fc.process("resp", "Return Response")

# Branch for No
fc.position_at(100, 340)
fc.process("err", "Return 401")

fc.connect("__start__", "auth")
fc.connect("auth", "valid")
fc.connect("valid", "proc", "Yes")
fc.connect("valid", "err", "No")
fc.connect("proc", "resp")

fc.save("auth_flow.excalidraw")

Example 3: Microservices Architecture

python

import sys, os
sys.path.insert(0, os.path.expanduser("~/.ai/agent/skills/excalidraw-diagrams/scripts"))
from excalidraw_generator import ArchitectureDiagram

arch = ArchitectureDiagram()

# Client layer
arch.user("client", "Client", x=400, y=50)

# Gateway
arch.service("gateway", "API Gateway", x=350, y=180, color="violet")

# Services row
arch.service("auth", "Auth Service", x=100, y=350, color="blue")
arch.service("users", "User Service", x=300, y=350, color="blue")
arch.service("orders", "Order Service", x=500, y=350, color="blue")
arch.service("notify", "Notification", x=700, y=350, color="cyan")

# Databases
arch.database("authdb", "Auth DB", x=100, y=500, color="green")
arch.database("userdb", "User DB", x=300, y=500, color="green")
arch.database("orderdb", "Order DB", x=500, y=500, color="green")

# Message queue
arch.component("queue", "Message Queue", x=600, y=450, color="orange")

# Connections
arch.connect("client", "gateway", "HTTPS")
arch.connect("gateway", "auth", "gRPC")
arch.connect("gateway", "users", "gRPC")
arch.connect("gateway", "orders", "gRPC")
arch.connect("auth", "authdb", "SQL")
arch.connect("users", "userdb", "SQL")
arch.connect("orders", "orderdb", "SQL")
arch.connect("orders", "queue", "publish")
arch.connect("queue", "notify", "subscribe")

arch.save("microservices.excalidraw")

Viewing the Output

After generating a .excalidraw file:

•Excalidraw.com: Go to https://excalidraw.com and drag the file onto the canvas
•VS Code: Install the "Excalidraw" extension, then open the file
•CLI: Use open filename.excalidraw on macOS to open with default app

Exporting to PNG

To embed diagrams in presentations or other documents, export them to PNG using Playwright.

Using the Export Script

bash

# First time setup: install dependencies
cd ~/.ai/agent/skills/excalidraw-diagrams/scripts
~/.ai/agent/skills/excalidraw-diagrams/bin/npm install
~/.ai/agent/skills/excalidraw-diagrams/bin/npx playwright install chromium

# Export to PNG
~/.ai/agent/skills/excalidraw-diagrams/bin/node scripts/export_playwright.js diagram.excalidraw output.png

How It Works

The Playwright export script:

•Opens excalidraw.com in a headless Chromium browser
•Loads your diagram via drag-and-drop simulation
•Fits the view to content (Shift+1)
•Screenshots the canvas at 1920x1200 resolution

Requirements

All required tools are provided in the skill's bin/ directory. No system PATH dependencies are needed.

Design Guidelines

Diagram Types

Choose the appropriate diagram type for your content:

Type	Use Case
Architecture diagrams	System, software, cloud infrastructure
Flowcharts	Process flows, decision trees
Sequence diagrams	API calls, message flows
Entity relationship diagrams	Database schemas
Network topology diagrams	Infrastructure layouts
Data flow diagrams	Information movement
State machine diagrams	State transitions
Mind maps	Brainstorming, concept exploration
Org charts	Team structures, hierarchies

Layout Principles

•Visual hierarchy: Guide the eye with size, color, and position
•Flow direction: Left-to-right or top-to-bottom for Western audiences
•Consistent spacing: Uniform gaps between similar elements
•Logical grouping: Related elements should be visually clustered
•Clear connection paths: Arrows should not cross unnecessarily
•Balanced composition: Distribute visual weight evenly
•Whitespace utilization: Don't crowd elements

Best Practices

Clarity

•One main concept per diagram
•Clear labels on all elements
•Minimal crossing lines
•Consistent terminology
•Legend for complex diagrams

Consistency

•Uniform element sizes for same-type components
•Consistent color meanings across diagrams
•Standard arrow directions
•Aligned text and elements
•Matching styles within diagram sets

Accessibility

•High contrast colors
•Readable font sizes (minimum 16px)
•Descriptive labels over icons alone
•Color-blind friendly palettes
•Clear visual hierarchy

Common Diagram Patterns

Architecture Diagram

•Services as rounded rectangles
•Databases as ellipses (cylinders conceptually)
•Users/clients as gray ellipses
•Cloud boundaries as dashed rectangles
•Data flow with labeled arrows

Flowchart

•Start/end as ellipses (green/red)
•Process steps as rectangles (blue)
•Decisions as diamonds (yellow/orange)
•Clear yes/no paths from decisions
•Swim lanes for responsibilities

Sequence Diagram

•Participants as rectangles at top
•Lifelines as vertical dashed lines
•Messages as horizontal arrows
•Activation boxes for processing
•Return values as dashed arrows

Layout Best Practices for Complex Diagrams

When creating dependency graphs, roadmaps, or diagrams with many nodes:

1. Use Visual Grouping Containers

Create semi-transparent background rectangles to group related elements:

•Use opacity 50 for subtle separation
•Color-code sections (blue=Q1, green=Q2, etc.)
•Background rectangles should be larger than content they contain

python

d.add_element({
    "type": "rectangle",
    "x": section_x, "y": section_y,
    "width": section_width, "height": section_height,
    "backgroundColor": "#a5d8ff",  # Light blue
    "fillStyle": "solid",
    "opacity": 50,
    "strokeWidth": 2,
})

2. Prefer Vertical Layouts Over Horizontal

•Stack logical groups (quarters, phases) vertically with 150-200px between sections
•Provides more horizontal space for arrows to route around content
•Horizontal layouts cramp content and force arrows through elements

3. Use Generous Spacing

Minimum spacing guidelines:

•Between rows: 90-120px
•Between nodes in same row: 30-50px
•Padding inside group containers: 40-60px

4. Spacing Reference Table

Element Type	Recommended Spacing
Between boxes in same row	50-80px horizontal
Between rows	80-120px vertical
Between logical sections	150-250px
Margin from background edge	20-40px
Arrow waypoint offset	30-50px from obstacles

5. Visual Hierarchy Through Color

•Group containers: Distinct colors at opacity 50
•Nodes: Same color as their parent group opacity 100
•Stroke: Consistent #1e1e1e (dark gray) for all elements

6. Arrow Routing

Route arrows around content, not through it:

•Use curved arrows with 1-2 intermediate waypoints (prefer fewer when possible)
•Arrows should bend to avoid crossing over boxes
•The arrow_between_routed() method handles this automatically

python

# Good: Routed arrow avoids obstacles
d.arrow_between_routed(source, target, label="data flow")

# Less good but acceptable if necessary: Elbowed arrows for orthogonal routing
d.arrow_between(source, target, routing="orthogonal")

7. Element Bindings

Prefer bound arrows.

Arrows can be bound to shapes so they stay connected when shapes are moved:

python

# Bindings are created automatically when using arrow methods
d.arrow_between(box1, box2)  # bound=True by default

# To create an unbound arrow (won't follow when shapes move)
d.arrow_between(box1, box2, bound=False)

7. Anti-Patterns to Avoid

•Grid-locked layouts: Allow offset positions for arrow routing space
•Straight-line arrows only: Direct arrows cross over content
•Horizontal cramming: Side-by-side layouts become unreadable
•Small boxes: Text hard to read; arrows can't connect cleanly
•No visual grouping: Without background sections, items feel disconnected
•Ignoring element binding: Unbound arrows don't move with boxes when editing