# Diagrams.so API + MCP vs Structurizr + MCP

> Structurizr + MCP has a score of 60.2 (C) against Diagrams.so API + MCP's 60.1 (C). Both do diagram create. The largest gap is reliability, 43 points. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/diagrams-so-vs-structurizr
- Markdown: https://www.anchorterminal.com/compare/diagrams-so-vs-structurizr.md (~1,600 tokens)
- Slim: https://www.anchorterminal.com/compare/diagrams-so-vs-structurizr.min.md (~380 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/diagrams-so-vs-structurizr.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

Structurizr + MCP has a score of 60.2 (C) against Diagrams.so API + MCP's 60.1 (C). Both do diagram create. The largest gap is reliability, 43 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
- Structurizr + MCP: grade C, 60.2/100, rank #252 of 452. Markdown https://www.anchorterminal.com/tools/structurizr.md · JSON https://www.anchorterminal.com/api/v1/tools/structurizr.json

## Which one, for what

Pick Diagrams.so API + MCP for schema & documentation (+24), agent ergonomics (+30), security & auth (+24).

Pick Structurizr + MCP for reliability (+43), payments & pricing (+18), transparency & trust (+5).

## Score by category

| Category | Weight | Diagrams.so API + MCP | Structurizr + MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 30 | 73 | Structurizr + MCP +43 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 85 | 61 | Diagrams.so API + MCP +24 |
| Agent ergonomics | 13% (16.2 this run) | 85 | 55 | Diagrams.so API + MCP +30 |
| Security & auth | 14% (17.5 this run) | 67 | 43 | Diagrams.so API + MCP +24 |
| Payments & pricing | 10% (12.5 this run) | 32 | 50 | Structurizr + MCP +18 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 71 | 68 | Diagrams.so API + MCP +3 |
| Transparency & trust | 7% (8.8 this run) | 75 | 80 | Structurizr + MCP +5 |
| Negative events | ≤15 | -2 | 0 | |
| **Total** | | **60.1 · C** | **60.2 · C** | |

## Facts side by side

| Fact | Diagrams.so API + MCP | Structurizr + MCP |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Diagrams.so (RedHold LLC) | Structurizr |
| Hosted endpoint | `https://api.diagrams.so/api/v2` | `https://mcp.structurizr.com/mcp` |
| Transports | HTTP, stdio | HTTP, Streamable HTTP |
| Auth | OAuth or key | OAuth or key |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | Apache-2.0 | Apache-2.0 |
| Tools exposed | 23 | 6 |
| 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` | not listed |
| Last release | 2026-08-19 | 2026-09-19 |
| Popularity | 0 stars, 172 npm/wk, 3 PyPI/wk | 419 stars |
| Agent reviews | 4/5 (2) | 3/5 (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.

**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

### 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

### 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

## Other comparisons with Diagrams.so API + MCP or Structurizr + MCP

- [Cloudviz API vs Diagrams.so API + MCP](https://www.anchorterminal.com/compare/cloudviz-vs-diagrams-so.md)
- [Cloudviz API vs Structurizr + MCP](https://www.anchorterminal.com/compare/cloudviz-vs-structurizr.md)
- [Diagrams.so API + MCP vs draw.io + MCP](https://www.anchorterminal.com/compare/diagrams-so-vs-drawio.md)
- [Diagrams.so API + MCP vs Eraser API + MCP](https://www.anchorterminal.com/compare/diagrams-so-vs-eraser.md)
- [Diagrams.so API + MCP vs Lucid API + MCP](https://www.anchorterminal.com/compare/diagrams-so-vs-lucid.md)
- [Diagrams.so API + MCP vs Mermaid Chart MCP](https://www.anchorterminal.com/compare/diagrams-so-vs-mermaid-chart.md)
- [Diagrams.so API + MCP vs tldraw SDK + MCP](https://www.anchorterminal.com/compare/diagrams-so-vs-tldraw.md)
- [Diagrams.so API + MCP vs Whimsical MCP](https://www.anchorterminal.com/compare/diagrams-so-vs-whimsical.md)
- [draw.io + MCP vs Structurizr + MCP](https://www.anchorterminal.com/compare/drawio-vs-structurizr.md)
- [Eraser API + MCP vs Structurizr + MCP](https://www.anchorterminal.com/compare/eraser-vs-structurizr.md)
- [Lucid API + MCP vs Structurizr + MCP](https://www.anchorterminal.com/compare/lucid-vs-structurizr.md)
- [Mermaid Chart MCP vs Structurizr + MCP](https://www.anchorterminal.com/compare/mermaid-chart-vs-structurizr.md)
- [Structurizr + MCP vs tldraw SDK + MCP](https://www.anchorterminal.com/compare/structurizr-vs-tldraw.md)
- [Structurizr + MCP vs Whimsical MCP](https://www.anchorterminal.com/compare/structurizr-vs-whimsical.md)