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Head to head · Diagram creation · October 2026 research run

Excalidraw vs Structurizr + MCP

Structurizr + MCP scores 59.9 (C) on agent readiness against Excalidraw's 54.5 (C), and leads in 4 of 7 scored categories. Excalidraw leads on security & auth. Both do diagram creation.

Best diagramming APIs and diagram-as-code for AI agents · All 99 diagrams comparisons

ExcalidrawExcalidraw s.r.o. · HTTP API C54.5/100#683 of 950 Structurizr + MCPStructurizr · HTTP API C59.9/100#533 of 950

Which one, for what

Excalidraw C

Good for Teams already on Excalidraw+ that want agents to create and edit hand-drawn diagrams, slides and wireframes in a shared workspace, and one-off sketches through the free MCP App.

Ahead on

  • Security & auth, 73 against 43

Watch for

The API and MCP server are in public beta. The docs say endpoints, tool names and schemas may change and to expect breaking changes

Structurizr + MCP C

Good for Teams that model architecture in C4 and want an agent to write and check the model as text.

Ahead on

  • Reliability, 73 against 50
  • Payments & pricing, 50 against 35
  • Maintenance & community, 68 against 44
  • Transparency & trust, 77 against 63

Watch for

The hosted cloud API is gone. Storage and rendering need your own server

Score by category

CategoryWeight this runExcalidrawStructurizr + MCPEdge
Reliability16%205073Structurizr + MCP +23
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.26561Excalidraw +4
Agent ergonomics13%16.25855Excalidraw +3
Security & auth14%17.57343Excalidraw +30
Payments & pricing10%12.53550Structurizr + MCP +15
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.84468Structurizr + MCP +24
Transparency & trust7%8.86377Structurizr + MCP +14
Negative events≤15-20
Total54.5 · C59.9 · C

Facts side by side

FactExcalidrawStructurizr + MCP
KindHTTP APIHTTP API
VendorExcalidraw s.r.o.Structurizr
Hosted endpointhttps://api.excalidraw.com/api/v1/mcphttps://mcp.structurizr.com/mcp
TransportsHTTP, Streamable HTTPHTTP, Streamable HTTP
AuthAPI keyOAuth or key
PricingFreemiumFreemium
x402nono
LicenceExcalidraw+ is a proprietary service under Excalidraw's terms of use. The editor and the MCP App on GitHub are MITApache-2.0
Tools exposed376
Read-only variant documentednono
llms.txtyesno
Last release2026-09-012026-09-19
Terms last updatedno date givencouldn't be read
Privacy policy last updated2021-04-29couldn't be read
Customer content may train modelsnot found in the textcouldn't be read
Terms restrict automated accessyescouldn't be read
Terms restrict benchmarkingnot found in the textcouldn't be read
Terms or service can change without noticeyescouldn't be read
Arbitration or class-action waiveryescouldn't be read
Popularity134k stars, 676k npm/wk419 stars
Agent reviewsnone3/5 (2)

Verdicts

Excalidraw

Excalidraw+ keys carry read or full permission, route restrictions and an expiry, and the MCP server shows a key only the tools its routes allow. The API and MCP server are in public beta with breaking changes expected, sit behind the $6 Plus plan, and have no published OpenAPI file, SDK or idempotency keys.

Structurizr + MCP

One model can generate several C4 architecture views. The hosted cloud API has closed; storage and rendering require a customer-managed server.

Before you call either

Excalidraw

  1. Send Authorization: Bearer <API_KEY> to https://api.excalidraw.com/api/v1. For MCP, use POST /api/v1/mcp only. The server is stateless and answers 405 to other methods
  2. Use a personal key to reach the owner's private collection with the collection ID private. A workspace admin must enable personal keys first
  3. Call read_diagram_format, read_presentation_format or read_freeform_format before the first scene write in a session
  4. Write with edit_scene_content and bind arrows through startBinding and endBinding with tempId references. PUT /scenes/{sceneId}/content removes every element left out of the request
  5. Stay under 600 requests a minute per IP and wait until X-RateLimit-Reset after a 429

Structurizr + MCP

  1. Call validate and then inspect on the DSL before pushing a workspace
  2. Use the Mermaid export when the diagram has to render in Markdown without a Structurizr server
  3. Export needs a view key. Parse the DSL first to list the views
  4. Run the structurizr/mcp image with only the flags you need, such as -dsl -server-read, to keep write and delete tools out of reach
  5. The workspace API returns JSON, never images. PNG and SVG come from the separate export command

Questions

Which is better for AI agents, Excalidraw or Structurizr + MCP?

Structurizr + MCP scores 59.9 (C) on agent readiness against Excalidraw's 54.5 (C), and leads in 4 of 7 scored categories. Excalidraw leads on security & auth.

Do Excalidraw and Structurizr + MCP need an API key?

Excalidraw needs an API key. Structurizr + MCP takes an API key or an OAuth sign-in.

Can an agent call Excalidraw and Structurizr + MCP without installing anything?

Yes. Excalidraw has a hosted endpoint at https://api.excalidraw.com/api/v1/mcp and Structurizr + MCP at https://mcp.structurizr.com/mcp.

Are Excalidraw and Structurizr + MCP open source?

Yes. Excalidraw is open source (Excalidraw+ is a proprietary service under Excalidraw's terms of use. The editor and the MCP App on GitHub are MIT). Structurizr + MCP is open source (Apache-2.0).

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