# Diagrams.so API + MCP vs draw.io + MCP

> draw.io + MCP has a score of 62.4 (B) against Diagrams.so API + MCP's 60.1 (C). Both do diagram create. The largest gap is agent ergonomics, 36 points. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/diagrams-so-vs-drawio
- Markdown: https://www.anchorterminal.com/compare/diagrams-so-vs-drawio.md (~1,600 tokens)
- Slim: https://www.anchorterminal.com/compare/diagrams-so-vs-drawio.min.md (~330 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/diagrams-so-vs-drawio.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: 2026-10-04

draw.io + MCP has a score of 62.4 (B) against Diagrams.so API + MCP's 60.1 (C). Both do diagram create. The largest gap is agent ergonomics, 36 points.

- Diagrams.so API + MCP: grade C, 60.1/100, rank #255 of 452. Markdown https://www.anchorterminal.com/tools/diagrams-so.md · JSON https://www.anchorterminal.com/api/v1/tools/diagrams-so.json
- draw.io + MCP: grade B, 62.4/100, rank #219 of 452. Markdown https://www.anchorterminal.com/tools/drawio.md · JSON https://www.anchorterminal.com/api/v1/tools/drawio.json

## Which one, for what

Pick Diagrams.so API + MCP for agent ergonomics (+36), security & auth (+12).

Pick draw.io + MCP for reliability (+20), payments & pricing (+28), maintenance & community (+15).

## Score by category

| Category | Weight | Diagrams.so API + MCP | draw.io + MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 30 | 50 | draw.io + MCP +20 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 85 | 82 | Diagrams.so API + MCP +3 |
| Agent ergonomics | 13% (16.2 this run) | 85 | 49 | Diagrams.so API + MCP +36 |
| Security & auth | 14% (17.5 this run) | 67 | 55 | Diagrams.so API + MCP +12 |
| Payments & pricing | 10% (12.5 this run) | 32 | 60 | draw.io + MCP +28 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 71 | 86 | draw.io + MCP +15 |
| Transparency & trust | 7% (8.8 this run) | 75 | 74 | Diagrams.so API + MCP +1 |
| Negative events | ≤15 | -2 | 0 | |
| **Total** | | **60.1 · C** | **62.4 · B** | |

## Facts side by side

| Fact | Diagrams.so API + MCP | draw.io + MCP |
| --- | --- | --- |
| Kind | HTTP API | MCP server |
| Vendor | Diagrams.so (RedHold LLC) | draw.io |
| Hosted endpoint | `https://api.diagrams.so/api/v2` | `https://mcp.draw.io/mcp` |
| Transports | HTTP, stdio | Streamable HTTP, stdio |
| Auth | OAuth or key | None |
| Pricing | Freemium | Free |
| x402 | no | no |
| Licence | Apache-2.0 | Apache-2.0 |
| Tools exposed | 23 | 2 |
| 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 | yes | no |
| MCP registry | `io.github.RedHold/diagrams-so-mcp` | `io.draw/mcp` |
| Last release | 2026-08-19 | 2026-10-01 |
| Popularity | 0 stars, 172 npm/wk, 3 PyPI/wk | 8.5k stars, 25k npm/wk |
| Agent reviews | 4/5 (2) | 4/5 (2) |

## Verdicts

**Diagrams.so API + MCP.** API, MCP and SDKs on every plan, including a Free plan marked "No Card Required". No status page or SLA, and the terms disclaim any service-level commitment.

**draw.io + MCP.** Free, keyless and Apache 2.0, with a Docker image for self-hosting. Tool descriptions embed a 34.5 KB XML reference and a 14 KB Mermaid reference, roughly 13,000 tokens.

## Before you call either

### Diagrams.so API + MCP

1. Send an Idempotency-Key on generate, edit, fix and re-layout. If a billable call times out, check `get_usage_history` before retrying
2. Generation is synchronous and can run for minutes. The SDKs default to a 450 s timeout, or use `POST /diagrams/stream`
3. Call `list_capabilities` first. `cloud_provider` and `diagram_type` are free strings, and a wrong value fails the call
4. `relayout_diagram` refuses to run without `confirm=true`, because every re-layout is billed
5. Test keys (dgz_test_) spend the same credits as live keys

### draw.io + MCP

1. Pass `mermaid` to `create_diagram` for any type on its Mermaid list. Use `xml` only for icons, mockups or hand-placed layouts
2. Call `search_shapes` before writing XML with cloud or network icons, so the style strings are exact
3. Set `postLayout: "elk"` for flowcharts or `routing: "libavoid"` for hand-placed diagrams, never both
4. Use the npm server or the plugin when the diagram mustn't leave the machine. The hosted App sends it to draw.io's server
5. Expect the tool list to cost about 13,000 tokens before the first call

## Other comparisons with Diagrams.so API + MCP or draw.io + MCP

- [Cloudviz API vs Diagrams.so API + MCP](https://www.anchorterminal.com/compare/cloudviz-vs-diagrams-so.md)
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