
excalidraw
Create Excalidraw diagrams as JSON files for flowcharts, user journeys, system architectures, wireframes, and visual documentation. Use when the user asks to create diagrams, flowcharts, visual representations, architecture diagrams, mind maps, or any Excalidraw-compatible visualizations. Outputs .excalidraw.json files that can be opened in excalidraw.com or any Excalidraw-compatible app.
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Install
Works with every agent the skills CLI supports.
npx skills add https://github.com/kv0906/cc-skills --skill excalidraw- 01
Install
Run the command in your project. The CLI asks which agents to install for.
- 02
Describe the task
Ask your agent for something this skill covers. It loads excalidraw automatically when relevant.
- 03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.
SKILL.md
The instructions your agent reads when the skill is triggered.
Excalidraw Diagram Generator
Create Excalidraw-compatible JSON diagrams. Output .excalidraw.json files.
JSON Schema
{
"type": "excalidraw",
"version": 2,
"source": "https://excalidraw.com",
"elements": [],
"appState": {
"gridSize": null,
"viewBackgroundColor": "#ffffff"
},
"files": {}
}
Coordinate System
- Origin: Top-left corner (0, 0)
- X-axis: Increases rightward
- Y-axis: Increases downward
- Unit: Pixels
Grid-Based Layout System
Use a 20px grid for alignment. Standard positions:
GRID_UNIT = 20
COLUMN_WIDTH = 200 # Element + gap
ROW_HEIGHT = 150 # Element + gap
Position formula:
x = START_X + (column * COLUMN_WIDTH)
y = START_Y + (row * ROW_HEIGHT)
Recommended START_X = 50, START_Y = 100
Standard Element Sizes
| Element | Width | Height | Use Case |
|---|---|---|---|
| Small box | 120 | 60 | Labels, simple steps |
| Standard box | 160 | 80 | Process steps |
| Large box | 200 | 100 | Detailed nodes |
| Wide box | 240 | 80 | Long text |
| Diamond | 100 | 100 | Decision points |
| Circle | 80 | 80 | Start/End nodes |
| Icon circle | 90 | 80 | With emoji |
Text Centering Formula
CRITICAL: To center text inside a shape:
text_x = shape_x + (shape_width - text_width) / 2
text_y = shape_y + (shape_height - text_height) / 2
Text Size Reference
| Font Size | Char Width | Line Height | Use |
|---|---|---|---|
| 11 | ~6px | 15px | Labels, annotations |
| 12 | ~7px | 16px | Secondary text |
| 14 | ~8px | 18px | Body text |
| 16 | ~9px | 20px | Primary text |
| 18 | ~10px | 24px | Headings |
| 20 | ~11px | 26px | Titles |
| 28 | ~16px | 35px | Icons/Emoji |
Estimate text_width: char_count * char_width
Estimate text_height: line_count * line_height
Centering Example
Shape: x=100, y=100, width=160, height=80
Text: "Process" (7 chars), fontSize=16
text_width = 7 * 9 = 63
text_height = 1 * 20 = 20
text_x = 100 + (160 - 63) / 2 = 148.5 ≈ 148
text_y = 100 + (80 - 20) / 2 = 130
Element Types
Common Properties (required for all)
{
"id": "unique-id",
"type": "rectangle",
"x": 100,
"y": 100,
"width": 160,
"height": 80,
"strokeColor": "#1e1e1e",
"backgroundColor": "transparent",
"fillStyle": "solid",
"strokeWidth": 2,
"roughness": 1,
"opacity": 100,
"angle": 0,
"seed": 100,
"version": 1,
"isDeleted": false,
"boundElements": null,
"link": null,
"locked": false
}
Type-Specific Properties
Rectangle: Add "roundness": {"type": 3} for rounded corners
Text:
{
"type": "text",
"text": "Content\nLine 2",
"fontSize": 16,
"fontFamily": 1,
"textAlign": "center",
"verticalAlign": "middle"
}
- fontFamily: 1=Virgil (hand), 2=Helvetica, 3=Cascadia (mono)
Arrow/Line:
{
"type": "arrow",
"points": [[0, 0], [100, 0]],
"startArrowhead": null,
"endArrowhead": "arrow"
}
- Points are relative to element's x,y
- Arrowheads:
null,"arrow","bar","dot","triangle"
Arrow Positioning
Horizontal Arrow (Left to Right)
From shape at (x1, y1, w1, h1) to shape at (x2, y2, w2, h2):
arrow_x = x1 + w1 # Right edge of source
arrow_y = y1 + h1/2 # Vertical center
gap = x2 - (x1 + w1) # Space between shapes
points = [[0, 0], [gap, 0]]
Vertical Arrow (Top to Bottom)
arrow_x = x1 + w1/2 # Horizontal center
arrow_y = y1 + h1 # Bottom edge of source
gap = y2 - (y1 + h1)
points = [[0, 0], [0, gap]]
Diagonal/Curved Arrow
points = [[0, 0], [dx/2, dy], [dx, dy]] # Curved path
Color Palette
| Color | Stroke | Background | Use |
|---|---|---|---|
| Blue | #1971c2 | #a5d8ff | Primary, info |
| Green | #2f9e44 | #b2f2bb | Success, start |
| Orange | #e8590c | #ffc9c9 | Warning, action |
| Red | #e03131 | #ffc9c9 | Error, end |
| Purple | #9c36b5 | #eebefa | Special, loop |
| Yellow | #f08c00 | #ffec99 | Highlight |
| Teal | #099268 | #96f2d7 | Secondary |
| Gray | #868e96 | #dee2e6 | Neutral, labels |
| Black | #1e1e1e | - | Text, borders |
Z-Order (Element Array Order)
Elements render in array order. First = back, last = front.
Correct order:
- Background shapes (containers, frames)
- Connection lines/arrows
- Foreground shapes (nodes, boxes)
- Text labels
- Icons/overlays
Layout Patterns
Horizontal Flow (Left to Right)
COL_GAP = 60 # Gap between elements
Element 1: x=50, y=100, w=160, h=80
Arrow 1: x=210, y=140, points=[[0,0],[60,0]]
Element 2: x=270, y=100, w=160, h=80
Arrow 2: x=430, y=140, points=[[0,0],[60,0]]
Element 3: x=490, y=100, w=160, h=80
Vertical Flow (Top to Bottom)
ROW_GAP = 50
Element 1: x=100, y=50, w=160, h=80
Arrow 1: x=180, y=130, points=[[0,0],[0,50]]
Element 2: x=100, y=180, w=160, h=80
Decision Branch (Diamond)
Diamond: x=300, y=200, w=100, h=100
Center: (350, 250)
Yes path (up-right):
arrow_x=350, arrow_y=200
points=[[0,0], [0,-50], [100,-50]]
No path (down-right):
arrow_x=350, arrow_y=300
points=[[0,0], [0,50], [100,50]]
Feedback Loop (Return Arrow)
From bottom-right back to left:
Start: (800, 400)
points=[
[0, 0], # Start
[0, 80], # Down
[-400, 80], # Left
[-400, -150] # Up to target
]
Complete Node Example
[
{
"id": "node1-box",
"type": "rectangle",
"x": 100, "y": 100, "width": 160, "height": 80,
"strokeColor": "#1971c2",
"backgroundColor": "#a5d8ff",
"fillStyle": "solid",
"strokeWidth": 2,
"roughness": 1,
"opacity": 100,
"angle": 0,
"seed": 100,
"version": 1,
"isDeleted": false,
"boundElements": [{"id": "arrow1", "type": "arrow"}],
"roundness": {"type": 3},
"link": null,
"locked": false
},
{
"id": "node1-text",
"type": "text",
"x": 130, "y": 130,
"width": 100, "height": 20,
"text": "Process Step",
"fontSize": 16,
"fontFamily": 1,
"textAlign": "center",
"verticalAlign": "middle",
"strokeColor": "#1e1e1e",
"backgroundColor": "transparent",
"fillStyle": "solid",
"strokeWidth": 1,
"roughness": 1,
"opacity": 100,
"angle": 0,
"seed": 101,
"version": 1,
"isDeleted": false,
"boundElements": null,
"link": null,
"locked": false
}
]
Positioning Checklist
Before generating:
- ☐ Define grid: START_X, START_Y, COLUMN_WIDTH, ROW_HEIGHT
- ☐ List all elements with row/column positions
- ☐ Calculate exact x,y using formulas
- ☐ Calculate text positions using centering formula
- ☐ Calculate arrow start points and relative endpoints
- ☐ Order elements correctly for z-order
- ☐ Assign unique IDs and incrementing seeds
Templates
- Basic flowchart:
assets/flowchart-template.excalidraw.json - Processing loop:
references/processing-loop-template.md - Element specs:
references/elements.md
Output
- Save as
.excalidraw.json - Copy to
/mnt/user-data/outputs/ - Tell user: "Open at excalidraw.com → Menu → Open"
FAQ
What does the excalidraw skill do?
Create Excalidraw diagrams as JSON files for flowcharts, user journeys, system architectures, wireframes, and visual documentation. Use when the user asks to create diagrams, flowcharts, visual representations, architecture diagrams, mind maps, or any Excalidraw-compatible visualizations. Outputs .excalidraw.json files that can be opened in excalidraw.com or any Excalidraw-compatible app.
How do I install excalidraw?
Run npx skills add https://github.com/kv0906/cc-skills --skill excalidraw in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/excalidraw/ (personal) or .claude/skills/excalidraw/ (project).
Which AI agents can use excalidraw?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is excalidraw safe to install?
No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.
Who maintains excalidraw?
It is published by kv0906 in kv0906/cc-skills. It has 50 recorded installs.
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