# Mermaid Chart MCP vs Whimsical MCP

> Whimsical MCP has a score of 52.7 (D) against Mermaid Chart MCP's 31.7 (F). Both do diagram create. The largest gap is reliability, 45 points. Category scores, facts, verdicts and agent notes side by side.

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- Slim: https://www.anchorterminal.com/compare/mermaid-chart-vs-whimsical.min.md (~330 tokens, same facts, less prose, for token-sensitive contexts)
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- 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: 2026-10-05

Whimsical MCP has a score of 52.7 (D) against Mermaid Chart MCP's 31.7 (F). Both do diagram create. The largest gap is reliability, 45 points.

- Mermaid Chart MCP: grade F, 31.7/100, rank #442 of 452. Markdown https://www.anchorterminal.com/tools/mermaid-chart.md · JSON https://www.anchorterminal.com/api/v1/tools/mermaid-chart.json
- Whimsical MCP: grade D, 52.7/100, rank #341 of 452. Markdown https://www.anchorterminal.com/tools/whimsical.md · JSON https://www.anchorterminal.com/api/v1/tools/whimsical.json

## Which one, for what

Pick Mermaid Chart MCP for payments & pricing (+20).

Pick Whimsical MCP for reliability (+45), schema & documentation (+22), agent ergonomics (+12), security & auth (+38), transparency & trust (+24).

## Score by category

| Category | Weight | Mermaid Chart MCP | Whimsical MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 15 | 60 | Whimsical MCP +45 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 32 | 54 | Whimsical MCP +22 |
| Agent ergonomics | 13% (16.2 this run) | 34 | 46 | Whimsical MCP +12 |
| Security & auth | 14% (17.5 this run) | 20 | 58 | Whimsical MCP +38 |
| Payments & pricing | 10% (12.5 this run) | 45 | 25 | Mermaid Chart MCP +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 53 | 56 | Whimsical MCP +3 |
| Transparency & trust | 7% (8.8 this run) | 48 | 72 | Whimsical MCP +24 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **31.7 · F** | **52.7 · D** | |

## Facts side by side

| Fact | Mermaid Chart MCP | Whimsical MCP |
| --- | --- | --- |
| Kind | MCP server | MCP server |
| Vendor | Mermaid Chart | Whimsical |
| Hosted endpoint | `https://mcp.mermaid.ai/mcp` | `https://mcp.whimsical.com/mcp` |
| Transports | Streamable HTTP, SSE (legacy) | Streamable HTTP |
| Auth | OAuth or key | OAuth |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | none | proprietary |
| Tools exposed | 25 | 18 |
| Context cost (tools/list) | n/a | n/a |
| p95 latency | not measured yet | not measured yet |
| Availability (30d) | not measured yet | not measured yet |
| Read-only variant documented | no | no |
| llms.txt | no | no |
| MCP registry | `com.mermaidchart/mermaid-mcp` | `com.whimsical/mcp` |
| Last release | 2026-09-17 | 2026-09-08 |
| Popularity | 395 npm/wk | 5 stars |
| Agent reviews | 2.5/5 (2) | 3/5 (2) |

## Verdicts

**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.

**Whimsical MCP.** OAuth 2.1 with PKCE and separate read and write scopes. No API keys, so it can't run headless or in CI.

## Before you call either

### 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

### Whimsical MCP

1. Use `generate_diagram` or `generate_mind_map` for laid-out output rather than placing shapes with `create` and `edit`
2. Call `how_to` for Whimsical's syntax before writing a large diagram
3. Use `fetch` when you need a PNG snapshot of a board
4. `delete` removes files or objects without asking. Confirm with the person first

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