Flowchart API

Free · No API key · Built for AI agents

Create beautiful, interactive flowcharts programmatically with a single API call. Perfect for AI agents, chatbots, automation scripts, and any tool that needs to visualize processes. Every flowchart gets a shareable link — no account required.

No API key

Just POST and go

Shareable links

Instant public URL

19 node types

Full flowchart toolkit

Rate: 30/hr

Generous free tier

Endpoints

POST/api/create-flowchartCreate a flowchart

GET/api/export/{format}Export as json, mermaid, svg, or png

POST/api/create-vennCreate a Venn diagram

GET/api/export-venn/{format}Export Venn as json or svg

POST/api/create-orgchartCreate an org chart

GET/api/export-orgchart/{format}Export org chart as json or svg

POST/api/create-piechartCreate a pie/donut chart

GET/api/export-piechart/{format}Export pie chart as json or svg

POST/api/create-mindmapCreate a mind map

GET/api/export-mindmap/{format}Export mind map as json or svg

GET/api/node-typesList all node types

GET/api/healthAPI status + endpoint list

GET/openapi.jsonOpenAPI 3.1 specification

Request Body

Field	Type	Required	Description
title	string	Yes	Flowchart title (max 200 chars)
description	string	No	Optional description (max 1000 chars)
createdBy	string	No	Attribution — your agent or app name
nodes	array	Yes	Array of node objects (1–100)
nodes[].id	string	Yes	Unique node identifier
nodes[].type	string	No	Node type (default: "process")
nodes[].label	string	Yes	Display label (max 200 chars)
nodes[].description	string	No	Node description (max 500 chars)
nodes[].x	number	No	X position (auto-layout if omitted)
nodes[].y	number	No	Y position (auto-layout if omitted)
edges	array	Yes	Array of edge objects (0–200)
edges[].from	string	Yes	Source node ID
edges[].to	string	Yes	Target node ID
edges[].label	string	No	Edge label (max 100 chars)
background	string	No	Hex color (#1a1a2e) or linear-gradient(135deg, #0f0c29, #302b63)
theme	string	No	Visual theme: default, neon, pastel, retro, ocean, brutalist, candy

Available Node Types

start

Beginning of the flow

end

End of the flow

process

Action or operation

decision

Yes/No branching point

io

Data input or output

delay

Wait or pause

subprocess

Nested process

task

Assignable task

bug

Bug or issue

email

Email action

meeting

Meeting or sync

approval

Approval step

milestone

Key milestone

deadline

Time-sensitive step

handoff

Team handoff

cost

Budget/cost node

note

Sticky note

textlabel

Text annotation

approvalGate

Approval gate checkpoint

Example Request

json

{
  "title": "User Signup Flow",
  "description": "How new users register on our platform",
  "createdBy": "My AI Agent",
  "theme": "ocean",
  "background": "#0c1222",
  "nodes": [
    { "id": "1", "type": "start", "label": "User visits site" },
    { "id": "2", "type": "process", "label": "Click Sign Up" },
    { "id": "3", "type": "io", "label": "Enter email & password" },
    { "id": "4", "type": "decision", "label": "Valid input?" },
    { "id": "5", "type": "process", "label": "Create account" },
    { "id": "6", "type": "email", "label": "Send verification email" },
    { "id": "7", "type": "end", "label": "Account active" },
    { "id": "8", "type": "process", "label": "Show error message" }
  ],
  "edges": [
    { "from": "1", "to": "2" },
    { "from": "2", "to": "3" },
    { "from": "3", "to": "4" },
    { "from": "4", "to": "5", "label": "Yes" },
    { "from": "4", "to": "8", "label": "No" },
    { "from": "5", "to": "6" },
    { "from": "6", "to": "7" },
    { "from": "8", "to": "3" }
  ]
}

Example Response

json

{
  "success": true,
  "flowId": "abc123xyz",
  "shareId": "k7Rm2xP9qWnE",
  "url": "https://freeflowcharts.app/view/k7Rm2xP9qWnE",
  "embed": "<iframe src=\"https://freeflowcharts.app/view/k7Rm2xP9qWnE\" width=\"800\" height=\"600\" frameborder=\"0\"></iframe>",
  "branding": "Powered by FreeFlowCharts — https://freeflowcharts.app"
}

Code Examples

cURL

bash

curl -X POST https://freeflowcharts.app/api/create-flowchart \
  -H "Content-Type: application/json" \
  -d '{
    "title": "My First API Flowchart",
    "nodes": [
      { "id": "1", "type": "start", "label": "Begin" },
      { "id": "2", "type": "process", "label": "Do something" },
      { "id": "3", "type": "end", "label": "Done" }
    ],
    "edges": [
      { "from": "1", "to": "2" },
      { "from": "2", "to": "3" }
    ]
  }'

Python

python

import requests

response = requests.post(
    "https://freeflowcharts.app/api/create-flowchart",
    json={
        "title": "Deployment Pipeline",
        "createdBy": "My Python Script",
        "nodes": [
            {"id": "1", "type": "start", "label": "Push to main"},
            {"id": "2", "type": "process", "label": "Run CI tests"},
            {"id": "3", "type": "decision", "label": "Tests pass?"},
            {"id": "4", "type": "process", "label": "Build Docker image"},
            {"id": "5", "type": "process", "label": "Deploy to staging"},
            {"id": "6", "type": "approval", "label": "QA approval"},
            {"id": "7", "type": "milestone", "label": "Production deploy"},
            {"id": "8", "type": "end", "label": "Live!"},
            {"id": "9", "type": "bug", "label": "Fix failing tests"},
        ],
        "edges": [
            {"from": "1", "to": "2"},
            {"from": "2", "to": "3"},
            {"from": "3", "to": "4", "label": "Yes"},
            {"from": "3", "to": "9", "label": "No"},
            {"from": "9", "to": "2"},
            {"from": "4", "to": "5"},
            {"from": "5", "to": "6"},
            {"from": "6", "to": "7"},
            {"from": "7", "to": "8"},
        ],
    },
)

data = response.json()
print(f"View your flowchart: {data['url']}")

JavaScript / TypeScript

javascript

const response = await fetch("https://freeflowcharts.app/api/create-flowchart", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    title: "Support Ticket Flow",
    createdBy: "My Agent",
    nodes: [
      { id: "1", type: "start", label: "Ticket received" },
      { id: "2", type: "decision", label: "Priority?" },
      { id: "3", type: "process", label: "Assign to on-call" },
      { id: "4", type: "process", label: "Add to queue" },
      { id: "5", type: "end", label: "Resolved" },
    ],
    edges: [
      { from: "1", to: "2" },
      { from: "2", to: "3", label: "High" },
      { from: "2", to: "4", label: "Low" },
      { from: "3", to: "5" },
      { from: "4", to: "5" },
    ],
  }),
});

const data = await response.json();
console.log("View:", data.url);

Export Endpoints

Export any flowchart by its shareId (returned when you create it).

/api/export/json?id=<shareId>

Structured flow data with nodes, edges, and metadata

application/json

/api/export/mermaid?id=<shareId>

Mermaid flowchart syntax — paste into GitHub, Notion, Obsidian

text/plain

/api/export/svg?id=<shareId>

Vector SVG with themed styling, colored nodes, and arrows

image/svg+xml

/api/export/png?id=<shareId>

1600px-wide PNG rendered server-side

image/png

bash

# Export as Mermaid syntax
curl "https://freeflowcharts.app/api/export/mermaid?id=k7Rm2xP9qWnE"

# Export as SVG image
curl "https://freeflowcharts.app/api/export/svg?id=k7Rm2xP9qWnE" -o flowchart.svg

# Export as PNG image
curl "https://freeflowcharts.app/api/export/png?id=k7Rm2xP9qWnE" -o flowchart.png

# Export as JSON data
curl "https://freeflowcharts.app/api/export/json?id=k7Rm2xP9qWnE"

# Override background on export
curl "https://freeflowcharts.app/api/export/png?id=k7Rm2xP9qWnE&bg=%231a1a2e" -o dark-blue.png

All export endpoints accept optional bg and theme query parameters to override the background or visual theme. Available themes: default, neon, pastel, retro, ocean, brutalist, candy.

Rate Limits

30flowcharts per hour per IP

No API key required. If you need higher limits, contact us.

Constraints

• Max 100 nodes per flowchart
• Max 200 edges per flowchart
• Edges referencing non-existent node IDs are silently dropped
• If x / y are omitted, nodes are auto-laid out in a grid
• Unknown node types default to process
• API-created flowcharts include a "Powered by FreeFlowCharts" branding bar

Venn Diagram API

Create Venn diagrams programmatically with circles and labels. Same rate limits, same simplicity.

POST /api/create-venn — Request Body

Field	Type	Required	Description
title	string	Yes	Venn diagram title (max 200 chars)
description	string	No	Optional description (max 1000 chars)
createdBy	string	No	Attribution — your agent or app name
circles	array	Yes	Array of circle objects (1–8)
circles[].id	string	Yes	Unique circle identifier
circles[].label	string	Yes	Circle label (max 100 chars)
circles[].cx	number	No	X center (auto if omitted)
circles[].cy	number	No	Y center (auto if omitted)
circles[].r	number	No	Radius 20–400 (auto if omitted)
circles[].color	string	No	Hex color (auto-assigned if omitted)
circles[].opacity	number	No	Fill opacity 0.05–1.0 (default: 0.35)
labels	array	No	Array of label objects (0–50)
labels[].id	string	Yes	Unique label identifier
labels[].text	string	Yes	Label text (max 200 chars)
labels[].x	number	No	X position
labels[].y	number	No	Y position
labels[].fontSize	number	No	Font size 8–48 (default: 14)
labels[].color	string	No	Hex color (default: #ffffff)
labels[].region	string	No	Region hint: A, AB, ABC, etc.
bgColor	string	No	Background hex color (default: #13131f)

Example — Create a Venn Diagram

bash

curl -X POST https://freeflowcharts.app/api/create-venn \
  -H "Content-Type: application/json" \
  -d '{
  "title": "Skills Overlap",
  "circles": [
    {"id": "A", "label": "Frontend", "color": "#3b82f6"},
    {"id": "B", "label": "Backend", "color": "#ef4444"},
    {"id": "C", "label": "Design", "color": "#22c55e"}
  ],
  "labels": [
    {"id": "l1", "text": "React", "x": 260, "y": 210, "color": "#93c5fd", "region": "A"},
    {"id": "l2", "text": "Node.js", "x": 520, "y": 210, "color": "#fca5a5", "region": "B"},
    {"id": "l3", "text": "Full-Stack", "x": 390, "y": 220, "color": "#ffffff", "region": "AB"}
  ]
}'

Venn Export Endpoints

/api/export-venn/json?id=<shareId>

Structured Venn data with circles, labels, and metadata

application/json

/api/export-venn/svg?id=<shareId>

Rendered SVG with circles, labels, grid, and branding

image/svg+xml

Venn Constraints

• Max 8 circles per Venn diagram
• Max 50 labels per Venn diagram
• Circles auto-position if cx/cy omitted
• Colors auto-assigned from a palette if omitted
• API-created Venn diagrams include branding

Org Chart API

Create hierarchical org charts from a flat list of nodes with parent relationships. Auto-layout tree structure. Same rate limits, same simplicity.

POST /api/create-orgchart — Request Body

Field	Type	Required	Description
title	string	No	Org chart title (max 200 chars, default: "Untitled Org Chart")
description	string	No	Optional description (max 1000 chars)
createdBy	string	No	Attribution — your agent or app name
background	string	No	Background color (default: #13131f)
nodes	array	Yes	Array of node objects (1–100)
nodes[].id	string	Yes	Unique node identifier
nodes[].label	string	Yes	Person or role name (max 200 chars)
nodes[].title	string	No	Job title (max 200 chars)
nodes[].parentId	string	No	ID of parent node (root if omitted or unmatched)
nodes[].color	string	No	Hex color (auto-assigned by depth if omitted)

Example — Create an Org Chart

bash

curl -X POST https://freeflowcharts.app/api/create-orgchart \
  -H "Content-Type: application/json" \
  -d '{
  "title": "My Team",
  "nodes": [
    {"id": "1", "label": "CEO", "title": "Chief Executive"},
    {"id": "2", "label": "CTO", "title": "Technology", "parentId": "1"},
    {"id": "3", "label": "CFO", "title": "Finance", "parentId": "1"}
  ]
}'

Org Chart Export Endpoints

/api/export-orgchart/json?id=<shareId>

Structured org chart data with nodes and metadata

application/json

/api/export-orgchart/svg?id=<shareId>

Rendered SVG with nodes, connectors, and branding

image/svg+xml

Org Chart Constraints

• Max 100 nodes per org chart
• Auto-layout tree if positions are not provided
• Nodes with an unmatched parentId are treated as roots
• Same rate limit: 30/hr per IP

Pie Chart API

Create pie or donut charts from labeled value slices. Colors and percentages are auto-computed. Same rate limits, same simplicity.

POST /api/create-piechart — Request Body

Field	Type	Required	Description
title	string	No	Pie chart title (max 200 chars, default: "Untitled Pie Chart")
description	string	No	Optional description (max 1000 chars)
createdBy	string	No	Attribution — your agent or app name
background	string	No	Background color (default: #13131f)
donut	boolean	No	Render as a donut chart (default: false)
showLegend	boolean	No	Show the legend (default: true)
slices	array	Yes	Array of slice objects (1–50)
slices[].label	string	Yes	Slice label (max 200 chars)
slices[].value	number	Yes	Non-negative numeric value
slices[].color	string	No	Hex color (auto-assigned if omitted)

Example — Create a Pie Chart

bash

curl -X POST https://freeflowcharts.app/api/create-piechart \
  -H "Content-Type: application/json" \
  -d '{
  "title": "Market Share",
  "slices": [
    {"label": "Product A", "value": 40},
    {"label": "Product B", "value": 30},
    {"label": "Other", "value": 30}
  ],
  "donut": true
}'

Pie Chart Export Endpoints

/api/export-piechart/json?id=<shareId>

Structured slice data with computed percentages and metadata

application/json

/api/export-piechart/svg?id=<shareId>

Rendered SVG pie/donut chart with legend and branding

image/svg+xml

Pie Chart Constraints

• Max 50 slices per pie chart
• Total of all slice values must be greater than 0
• Same rate limit: 30/hr per IP

Mind Map API

Create radial mind maps from a flat list of nodes with parent relationships. Auto radial layout. Same rate limits, same simplicity.

POST /api/create-mindmap — Request Body

Field	Type	Required	Description
title	string	No	Mind map title (max 200 chars, default: "Untitled Mind Map")
description	string	No	Optional description (max 1000 chars)
createdBy	string	No	Attribution — your agent or app name
background	string	No	Background color (default: #13131f)
nodes	array	Yes	Array of node objects (1–100)
nodes[].id	string	Yes	Unique node identifier
nodes[].label	string	Yes	Idea/topic text (max 200 chars)
nodes[].parentId	string	No	ID of parent node (root if omitted or unmatched)
nodes[].color	string	No	Hex color (auto-assigned by branch if omitted)

Example — Create a Mind Map

bash

curl -X POST https://freeflowcharts.app/api/create-mindmap \
  -H "Content-Type: application/json" \
  -d '{
  "title": "Project Ideas",
  "nodes": [
    {"id": "1", "label": "Main Topic"},
    {"id": "2", "label": "Branch A", "parentId": "1"},
    {"id": "3", "label": "Branch B", "parentId": "1"}
  ]
}'

Mind Map Export Endpoints

/api/export-mindmap/json?id=<shareId>

Structured node data with metadata

application/json

/api/export-mindmap/svg?id=<shareId>

Rendered SVG with curved connectors and branding

image/svg+xml

Mind Map Constraints

• Max 100 nodes per mind map
• Auto radial layout around the root node(s)
• Same rate limit: 30/hr per IP

Error Responses

Status	Meaning
400	Bad request — missing or invalid fields
404	Flowchart not found (export endpoints)
405	Method not allowed — use POST for create, GET for export
429	Rate limit exceeded — max 30/hr
500	Internal server error

Skill Downloads

Give your AI agent the FreeFlowCharts skill — everything it needs to create and export flowcharts.

SKILL.md

Plain text — readable by any agent, Claude, Cascade, or human

GitHub API Repo

Examples, themes guide, node types, changelog

Add as Gemini skill (enter root URL):

bash

https://freeflowcharts.app

Discovery & Machine-Readable Docs

For agents and tools that need to discover the API programmatically:

/openapi.jsonFull OpenAPI 3.1 specification with schemas, examples, and all endpoints

/SKILL.mdSkill file with YAML frontmatter — complete API reference for agents

/.well-known/ai-plugin.jsonChatGPT/OpenAI plugin manifest

/api/healthAPI status, version, and complete endpoint listing

/api/node-typesAll 19 supported node types with descriptions and colors

/llms.txtStructured site info for LLM crawlers — includes API quick-start

/ai.txtAI crawling policy

Use Cases

AI Agents & Chatbots

Let your AI generate visual flowcharts from conversations and return shareable links to users.

CI/CD Pipelines

Auto-generate a visual pipeline diagram after each deploy. Share with your team in Slack.

Documentation Tools

Programmatically create flowcharts for your docs. Embed them with the provided iframe code.

Education Platforms

Generate visual concept maps and decision trees for students from structured course data.

Questions? Feature requests? We'd love to hear from you.

Try FreeFlowCharts Read the blog