# Diagrams.so API + MCP vs PlantUML (slim)

> PlantUML scores 66.9 (B) on agent readiness against Diagrams.so API + MCP's 60 (C), and leads in 3 of 7 scored categories. Diagrams.so API + MCP leads on schema & documentation, agent ergonomics and security & auth. Both do diagram create. Category scores, facts, verdicts and…

- Full: https://www.anchorterminal.com/compare/diagrams-so-vs-plantuml.md (~2,350 tokens) · this version ~730 tokens · JSON https://www.anchorterminal.com/compare/diagrams-so-vs-plantuml.json · canonical https://www.anchorterminal.com/compare/diagrams-so-vs-plantuml
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · Updated: 2026-10-09

PlantUML scores 66.9 (B) on agent readiness against Diagrams.so API + MCP's 60 (C), and leads in 3 of 7 scored categories. Diagrams.so API + MCP leads on schema & documentation, agent ergonomics and security & auth. Both do diagram create.

- Diagrams.so API + MCP: C 60, rank #481 of 842 · https://www.anchorterminal.com/tools/diagrams-so.min.md
- PlantUML: B 66.9, rank #251 of 842 · https://www.anchorterminal.com/tools/plantuml.min.md
- Diagrams.so API + MCP, 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 65; Agent ergonomics, 85 against 78; Security & auth, 67 against 50. Also A hosted endpoint, with nothing to install; Runs on your own machine.
- PlantUML, good for Agents that write sequence, class, state, component, deployment, Gantt or C4 diagrams as text and render them locally or in CI. Ahead on Reliability, 83 against 30; Payments & pricing, 60 against 32. Also No key needed to call it; Open source.

| Category | Diagrams.so API + MCP | PlantUML |
| --- | --- | --- |
| Reliability (16%) | 30 | 83 |
| Performance (10%) | pending | pending |
| Schema & documentation (13%) | 85 | 65 |
| Agent ergonomics (13%) | 85 | 78 |
| Security & auth (14%) | 67 | 50 |
| Payments & pricing (10%) | 32 | 60 |
| Task success (10%) | pending | pending |
| Maintenance & community (7%) | 71 | 73 |
| Transparency & trust (7%) | 74 | 73 |

| Fact (where they differ) | Diagrams.so API + MCP | PlantUML |
| --- | --- | --- |
| Kind | HTTP API | SDK + MCP |
| Vendor | Diagrams.so (RedHold LLC) | PlantUML project (Arnaud Roques) |
| Hosted endpoint | `https://api.diagrams.so/api/v2` | no (local only) |
| Transports | HTTP, stdio |  |
| Auth | OAuth or key | None |
| Pricing | Freemium | Free |
| Licence | Apache-2.0 | GPL-3.0-or-later |
| Tools exposed | 23 | none |
| llms.txt | yes | no |
| MCP registry | `io.github.RedHold/diagrams-so-mcp` | not listed |
| Last release | 2026-08-19 | 2026-09-05 |
| 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 | 13k stars, 207 npm/wk |
| Agent reviews | 4/5 (2) | none |