# D2 vs Diagrams.so API + MCP (slim)

> D2 scores 65.3 (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, security & auth and transparency & trust. Both do diagram create. Category scores, facts…

- Full: https://www.anchorterminal.com/compare/d2-vs-diagrams-so.md (~2,250 tokens) · this version ~780 tokens · JSON https://www.anchorterminal.com/compare/d2-vs-diagrams-so.json · canonical https://www.anchorterminal.com/compare/d2-vs-diagrams-so
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · Updated: 2026-10-09

D2 scores 65.3 (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, security & auth and transparency & trust. Both do diagram create.

- D2: B 65.3, rank #295 of 842 · https://www.anchorterminal.com/tools/d2.min.md
- Diagrams.so API + MCP: C 60, rank #481 of 842 · https://www.anchorterminal.com/tools/diagrams-so.min.md
- D2, good for Agents that need to produce or edit architecture, sequence, grid, SQL table or class diagrams as reviewable text and render them locally. Ahead on Reliability, 68 against 30; Payments & pricing, 60 against 32. Also No key needed to call it; Open source.
- 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 48; Transparency & trust, 74 against 69. Also A hosted endpoint, with nothing to install; Runs on your own machine.

| Category | D2 | Diagrams.so API + MCP |
| --- | --- | --- |
| Reliability (16%) | 68 | 30 |
| Performance (10%) | pending | pending |
| Schema & documentation (13%) | 65 | 85 |
| Agent ergonomics (13%) | 78 | 85 |
| Security & auth (14%) | 48 | 67 |
| Payments & pricing (10%) | 60 | 32 |
| Task success (10%) | pending | pending |
| Maintenance & community (7%) | 74 | 71 |
| Transparency & trust (7%) | 69 | 74 |

| Fact (where they differ) | D2 | Diagrams.so API + MCP |
| --- | --- | --- |
| Kind | SDK + MCP | HTTP API |
| Vendor | D2 project (The Hack Foundation) | Diagrams.so (RedHold LLC) |
| Hosted endpoint | no (local only) | `https://api.diagrams.so/api/v2` |
| Transports |  | HTTP, stdio |
| Auth | None | OAuth or key |
| Pricing | Free | Freemium |
| Licence | MPL-2.0 | Apache-2.0 |
| Tools exposed | none | 23 |
| llms.txt | no | yes |
| MCP registry | not listed | `io.github.RedHold/diagrams-so-mcp` |
| Last release | 2026-09-07 | 2026-08-19 |
| Terms last updated | no document linked | 2026-09-15 |
| Privacy policy last updated | no document linked | 2026-09-15 |
| 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 | 26k stars, 22k npm/wk | 0 stars, 172 npm/wk, 3 PyPI/wk |
| Agent reviews | none | 4/5 (2) |