AI Diagram Generator
Commercial use OK
380+ models
No watermark
No sign-up needed
Model:
+ GPT-5, Claude, Gemini
Describe a flow, system, or relationship and the AI generates Mermaid.js code that renders to a clean diagram. Embed in GitHub READMEs, Notion, Confluence, Obsidian.
Generated Diagram
What you can diagram
Process flows
Onboarding, checkout, support escalation, ETL pipelines.
System architecture
Class diagrams, sequence diagrams, ER schemas — engineer-friendly.
Project plans
Gantt charts and roadmaps that drop into Notion or Confluence.
Advanced options
Result
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Create diagrams with AI. Flowcharts, mind maps, and more.
How to Use AI Diagram Generator
1
Enter your input
Type text, upload a file, or describe what you want. No account needed.
2
Click generate
Our AI processes your request in seconds using the best open-source models.
3
Download & share
Download, copy, or share your result. Free for personal and commercial use.
Use this tool via API
Automate this tool from your own code. OpenAI-compatible REST endpoint, Bearer-token auth, no extra SDK required. Token costs match the web interface.
curl -X POST https://api.free.ai/v1/image/generate/ \
-H "Authorization: Bearer sk-free-..." \
-H "Content-Type: application/json" \
-d '{"prompt": "A modern minimalist logo for a coffee shop", "model": "flux-schnell"}'AI Diagram Generator — FAQ
Describe a flow, system, or relationship in plain English; pick a diagram-type chip (Flowchart, Sequence, Class, ER, Mind Map, Gantt, State, User Journey); choose a layout direction and color theme; the AI generates valid Mermaid.js code that renders inline as an SVG. Copy the code into GitHub READMEs, Notion, Confluence, Obsidian, or Markdown — anywhere Mermaid is supported.
Yes. Each diagram costs ~200 tokens from your daily pool (2,500 guest, 10,000 signed-up). No watermark, no subscription, no signup required. Mermaid Chart and Lucidchart charge $10-99/month for similar AI features.
Eight types: Flowcharts (TD/LR/BT/RL directions), Sequence diagrams (with actors and lifelines), Class diagrams (UML inheritance + composition), ER diagrams (database schemas with cardinality), Mind maps, Gantt charts (project timelines), State diagrams (stateMachine v2 syntax), and User Journey maps. All compile to standard Mermaid.js syntax.
Yes — the raw Mermaid code is shown below the rendered SVG. Copy it, edit in your preferred Mermaid editor (mermaid.live, VS Code Mermaid extension, GitHub native renderer), and paste back. The AI gets you 80% there — manual tweaks like reordering nodes or fine-tuning labels are usually faster than re-prompting.
Yes. Wrap the code in ```mermaid fences and GitHub renders it natively in any .md file. Same for GitLab, Bitbucket, Notion (via /code mermaid), Obsidian, Joplin, HackMD, and Forgejo. The Download SVG button gives you a vector you can drop into Confluence, Google Docs, or any presentation.
Lucidchart ($9-21/mo) and Miro ($8-16/mo) are full visual canvas tools with drag-and-drop and live collaboration. Draw.io is free but manual. Free.ai generates the diagram code from a description — best when you want speed and code-as-source-of-truth (Mermaid in git diffs nicely, drag-and-drop tools do not). Combine: prototype here, polish in Lucidchart.
Yes — pick the ER Diagram chip and describe your tables and relationships ("users have many posts, posts belong to a category, categories have a parent_id self-reference"). The AI outputs valid erDiagram syntax with cardinality (one-to-many, many-to-many) and foreign key annotations. Paste into a README to keep schema docs in sync with the codebase.
Yes — describe the actors and the message sequence ("client calls /auth/login, server validates, server calls Redis to cache the session, server returns JWT"). The AI generates a Mermaid sequenceDiagram with proper participant declarations, sync vs async arrows, and activation lifelines. Great for documenting OAuth flows, webhook handshakes, and microservice handoffs.
Default export is SVG (vector — scales infinitely). For PNG, open the SVG in any browser, right-click → Save image as → PNG, or use an online SVG-to-PNG converter. Or paste the Mermaid code into mermaid.live and use their PNG export. SVG is preferred for documentation since it never pixelates.
For up to ~20 nodes the AI gets it right on the first try. For 50+ node systems, generate the high-level diagram first, then recursively expand each major branch. Mermaid syntax is strict — if the render fails, the raw code is still shown so you can tweak it manually. Most failures are missing semicolons or unescaped special chars.
Yes — describe your diagram in any of the 99 supported languages. The Mermaid code uses your language for node labels (Mermaid handles Unicode fine). Diagram-type keywords (flowchart TD, sequenceDiagram, etc.) stay in English since Mermaid syntax requires that, but every label, edge, and note can be in your language.
Yes — POST to /v1/chat/ with the Mermaid system prompt asking for code-only output, billed at ~200 tokens per diagram. Useful for generating per-PR sequence diagrams in CI, syncing ER diagrams with schema migrations, or building docs sites from code annotations. Bearer auth via /developer/, full snippets at /api/.
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