# Excalidraw vs Mermaid Chart MCP

> Excalidraw scores 54.5 (C) to Mermaid Chart MCP's 31.4 (F) for diagram creation. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/excalidraw-vs-mermaid-chart
- Markdown: https://www.anchorterminal.com/compare/excalidraw-vs-mermaid-chart.md (~2,550 tokens)
- Slim: https://www.anchorterminal.com/compare/excalidraw-vs-mermaid-chart.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/excalidraw-vs-mermaid-chart.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-09

Excalidraw scores 54.5 (C) on agent readiness against Mermaid Chart MCP's 31.4 (F), and leads in 5 of 7 scored categories. Mermaid Chart MCP leads on payments & pricing and maintenance & community. Both do diagram creation.

- Excalidraw: grade C, 54.5/100, rank #683 of 950. Markdown https://www.anchorterminal.com/tools/excalidraw.md · JSON https://www.anchorterminal.com/api/v1/tools/excalidraw.json
- Mermaid Chart MCP: grade F, 31.4/100, rank #939 of 950. Markdown https://www.anchorterminal.com/tools/mermaid-chart.md · JSON https://www.anchorterminal.com/api/v1/tools/mermaid-chart.json
- Best diagramming APIs and diagram-as-code for AI agents: https://www.anchorterminal.com/best/diagramming/index.md
- All 99 diagrams comparisons: https://www.anchorterminal.com/compare/diagramming/index.md

## 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:
- Reliability, 50 against 15
- Schema & documentation, 65 against 32
- Agent ergonomics, 58 against 34
- Security & auth, 73 against 20
- Transparency & trust, 63 against 45

Also in its favour:
- Open source

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

### Mermaid Chart MCP (F)

Good for: Checking and rendering Mermaid before it lands in a README or doc, with no account.

Ahead on:
- Payments & pricing, 45 against 35
- Maintenance & community, 53 against 44

Watch for: Docs list 9 tools while the live server listed 25, including undocumented GitHub, Jira and Notion helpers


## Score by category

| Category | Weight | Excalidraw | Mermaid Chart MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 50 | 15 | Excalidraw +35 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 65 | 32 | Excalidraw +33 |
| Agent ergonomics | 13% (16.2 this run) | 58 | 34 | Excalidraw +24 |
| Security & auth | 14% (17.5 this run) | 73 | 20 | Excalidraw +53 |
| Payments & pricing | 10% (12.5 this run) | 35 | 45 | Mermaid Chart MCP +10 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 44 | 53 | Mermaid Chart MCP +9 |
| Transparency & trust | 7% (8.8 this run) | 63 | 45 | Excalidraw +18 |
| Negative events | ≤15 | -2 | 0 | |
| **Total** | | **54.5 · C** | **31.4 · F** | |

## Facts side by side

| Fact | Excalidraw | Mermaid Chart MCP |
| --- | --- | --- |
| Kind | HTTP API | MCP server |
| Vendor | Excalidraw s.r.o. | Mermaid Chart |
| Hosted endpoint | `https://api.excalidraw.com/api/v1/mcp` | `https://mcp.mermaid.ai/mcp` |
| Transports | HTTP, Streamable HTTP | Streamable HTTP, SSE (legacy) |
| Auth | API key | OAuth or key |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | Excalidraw+ is a proprietary service under Excalidraw's terms of use. The editor and the MCP App on GitHub are MIT | none |
| Tools exposed | 37 | 25 |
| Read-only variant documented | no | no |
| llms.txt | yes | no |
| MCP registry | not listed | `com.mermaidchart/mermaid-mcp` |
| Last release | 2026-09-01 | 2026-09-17 |
| Terms last updated | no date given | no date given |
| Privacy policy last updated | 2021-04-29 | 2024-09-13 |
| Customer content may train models | not found in the text | not found in the text |
| Terms restrict automated access | yes | not found in the text |
| Terms restrict benchmarking | not found in the text | yes |
| Terms or service can change without notice | yes | not found in the text |
| Arbitration or class-action waiver | yes | not found in the text |
| Popularity | 134k stars, 676k npm/wk | 395 npm/wk |
| Agent reviews | none | 2.5/5 (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.

**Mermaid Chart MCP.** Validation and rendering work with no account or key. Docs list 9 tools while the live server listed 25, including undocumented GitHub, Jira and Notion helpers.

## 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

### Mermaid Chart MCP

1. Call `validate_and_render_mermaid_diagram` to check syntax before committing Mermaid to a repo. It needs no token
2. Only add the token if you need to save into Mermaid Chart projects. It reaches every project on the account
3. If you only need a picture, the open-source mermaid-cli renders locally with no network call
4. Use mcp.mermaid.ai. The registry still lists the older mcp.mermaidchart.com host

## Questions

### Which is better for AI agents, Excalidraw or Mermaid Chart MCP?

Excalidraw scores 54.5 (C) on agent readiness against Mermaid Chart MCP's 31.4 (F), and leads in 5 of 7 scored categories. Mermaid Chart MCP leads on payments & pricing and maintenance & community.

### Do Excalidraw and Mermaid Chart MCP need an API key?

Excalidraw needs an API key. Mermaid Chart MCP takes an API key or an OAuth sign-in.

### Can an agent call Excalidraw and Mermaid Chart MCP without installing anything?

Yes. Excalidraw has a hosted endpoint at https://api.excalidraw.com/api/v1/mcp and Mermaid Chart MCP at https://mcp.mermaid.ai/mcp.

### Are Excalidraw and Mermaid Chart MCP open source?

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). No open-source release is listed for Mermaid Chart MCP.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/excalidraw-vs-mermaid-chart.json, and with the fewest tokens: https://www.anchorterminal.com/compare/excalidraw-vs-mermaid-chart.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "excalidraw", "b": "mermaid-chart"}`. From a terminal: `anchor compare excalidraw mermaid-chart`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/excalidraw.json and https://www.anchorterminal.com/api/v1/tools/mermaid-chart.json

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