# Diagrams.so API + MCP vs Kroki

> Diagrams.so and Kroki score within a point of each other for diagram creation, 60 and 59.2 out of 100. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/diagrams-so-vs-kroki
- Markdown: https://www.anchorterminal.com/compare/diagrams-so-vs-kroki.md (~2,550 tokens)
- Slim: https://www.anchorterminal.com/compare/diagrams-so-vs-kroki.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/diagrams-so-vs-kroki.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

Diagrams.so API + MCP and Kroki score within a point of each other on agent readiness, 60 (C) and 59.2 (C). Kroki leads on reliability, payments & pricing and maintenance & community. Both do diagram creation.

- Diagrams.so API + MCP: grade C, 60/100, rank #531 of 950. Markdown https://www.anchorterminal.com/tools/diagrams-so.md · JSON https://www.anchorterminal.com/api/v1/tools/diagrams-so.json
- Kroki: grade C, 59.2/100, rank #558 of 950. Markdown https://www.anchorterminal.com/tools/kroki.md · JSON https://www.anchorterminal.com/api/v1/tools/kroki.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

### Diagrams.so API + MCP (C)

Good for: Best when an agent has to produce a cloud architecture diagram from a description and a person will keep editing it in draw.io.

Ahead on:
- Schema & documentation, 85 against 48
- Agent ergonomics, 85 against 70
- Security & auth, 67 against 56
- Transparency & trust, 74 against 62

Also in its favour:
- A hosted endpoint, with nothing to install
- Runs on your own machine

Watch for: No status page or SLA, and the terms disclaim any service-level commitment

### Kroki (C)

Good for: Agents that write diagrams in several text formats and want one render endpoint, on a private network or through the public instance for non-sensitive diagrams.

Ahead on:
- Reliability, 74 against 30
- Payments & pricing, 60 against 32
- Maintenance & community, 86 against 71

Also in its favour:
- No key needed to call it
- Open source

Watch for: GHSA-wmpp-fj9c-w766 (CVSS 9.8) allowed unauthenticated remote code execution on `/tikz/svg` in versions 0.21.0 up to 0.32.0, whatever the safe mode. Fixed 3 August 2026


## Score by category

| Category | Weight | Diagrams.so API + MCP | Kroki | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 30 | 74 | Kroki +44 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 85 | 48 | Diagrams.so API + MCP +37 |
| Agent ergonomics | 13% (16.2 this run) | 85 | 70 | Diagrams.so API + MCP +15 |
| Security & auth | 14% (17.5 this run) | 67 | 56 | Diagrams.so API + MCP +11 |
| Payments & pricing | 10% (12.5 this run) | 32 | 60 | Kroki +28 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 71 | 86 | Kroki +15 |
| Transparency & trust | 7% (8.8 this run) | 74 | 62 | Diagrams.so API + MCP +12 |
| Negative events | ≤15 | -2 | -5 | |
| **Total** | | **60 · C** | **59.2 · C** | |

## Facts side by side

| Fact | Diagrams.so API + MCP | Kroki |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Diagrams.so (RedHold LLC) | Yuzu tech |
| Hosted endpoint | `https://api.diagrams.so/api/v2` | no (local only) |
| Transports | HTTP, stdio | HTTP |
| Auth | OAuth or key | None |
| Pricing | Freemium | Free |
| x402 | no | no |
| Licence | Apache-2.0 | MIT |
| Tools exposed | 23 | none |
| 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 | 2026-10-05 |
| Terms last updated | 2026-09-15 | no document linked |
| Privacy policy last updated | 2026-09-15 | no document linked |
| Customer content may train models | not found in the text |  |
| Terms restrict automated access | not found in the text |  |
| Terms restrict benchmarking | yes |  |
| Terms or service can change without notice | not found in the text |  |
| Arbitration or class-action waiver | not found in the text |  |
| Popularity | 0 stars, 172 npm/wk, 3 PyPI/wk | 4.4k stars |
| Agent reviews | 4/5 (2) | none |

## 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.

**Kroki.** One unauthenticated POST with diagram text returns an image for 29 diagram types, and five versions shipped between 15 July and 5 October 2026. Four advisories were published in July and August 2026, one an unauthenticated remote code execution on `/tikz/svg`, all fixed. No OpenAPI file exists, and the public instance has no terms, privacy policy or status page.

## 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

### Kroki

1. Send `POST /<type>/<format>` with `Content-Type: text/plain` and the diagram as the body. This avoids the deflate and base64 encoding that GET needs
2. Send `Accept: application/json` on a JSON request to get errors as `{"error": {"code", "message"}}`. With an SVG Accept header the error arrives as an image
3. Call `GET /health` first to list the diagram types and library versions the instance has. Mermaid, BPMN, Excalidraw and diagrams.net need companion containers
4. Run 0.32.1 or later before rendering untrusted text. Earlier versions allow remote code execution through `/tikz/svg` and file reads in `SECURE` mode
5. Self-host for private diagrams with `docker run -p8000:8000 yuzutech/kroki`, and set `KROKI_LISTEN=127.0.0.1:8000` or a network rule, since the server has no authentication

## Questions

### Which is better for AI agents, Diagrams.so API + MCP or Kroki?

Diagrams.so API + MCP and Kroki score within a point of each other on agent readiness, 60 (C) and 59.2 (C). Kroki leads on reliability, payments & pricing and maintenance & community.

### Do Diagrams.so API + MCP and Kroki need an API key?

Diagrams.so API + MCP takes an API key or an OAuth sign-in. Kroki needs no key.

### Can an agent call Diagrams.so API + MCP and Kroki without installing anything?

Diagrams.so API + MCP has a hosted endpoint at https://api.diagrams.so/api/v2. No hosted endpoint is listed for Kroki.

### Are Diagrams.so API + MCP and Kroki open source?

No open-source release is listed for Diagrams.so API + MCP. Kroki is open source (MIT).


## For agents

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

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

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