# D2 vs ExcaliClaw

> D2 scores 65.3 (B) to ExcaliClaw's 51.4 (D) for diagrams as code. Prices, MCP, x402, uptime and agent notes side by side.

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- API: https://www.anchorterminal.com/api/v1/index.json
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- Updated: 2026-10-14

D2 scores 65.3 (B) on agent readiness against ExcaliClaw's 51.4 (D), and leads in every scored category. Both do diagrams as code.

- D2: grade B, 65.3/100, rank #343 of 1084. Markdown https://www.anchorterminal.com/tools/d2.md · JSON https://www.anchorterminal.com/api/v1/tools/d2.json
- ExcaliClaw: grade D, 51.4/100, rank #804 of 1084. Markdown https://www.anchorterminal.com/tools/excaliclaw.md · JSON https://www.anchorterminal.com/api/v1/tools/excaliclaw.json
- Best diagramming APIs and diagram-as-code for AI agents: https://www.anchorterminal.com/best/diagramming/index.md
- All 128 diagrams comparisons: https://www.anchorterminal.com/compare/diagramming/index.md

## Which one, for what

### D2 (B)

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:
- Agent ergonomics, 78 against 55
- Security & auth, 48 against 40
- Payments & pricing, 60 against 30
- Maintenance & community, 74 against 54
- Transparency & trust, 69 against 45

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

Watch for: No 1.0 release. The maintainer lists a stable 1.0 with a formal grammar as a goal, and 0.8.2 changed Dagre and ELK layout output

### ExcaliClaw (D)

Good for: An agent that turns structure (nodes and edges, ER tables, sequence messages, Mermaid, docker-compose files) into editable hand-drawn diagrams in a shared workspace.

Also in its favour:
- A hosted endpoint, with nothing to install

Watch for: excaliclaw.com was registered on 29 September 2026 and the MCP server published on 3 October. Status monitoring covers 11 days


## Score by category

| Category | Weight | D2 | ExcaliClaw | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 68 | 65 | D2 +3 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 65 | 62 | D2 +3 |
| Agent ergonomics | 13% (16.2 this run) | 78 | 55 | D2 +23 |
| Security & auth | 14% (17.5 this run) | 48 | 40 | D2 +8 |
| Payments & pricing | 10% (12.5 this run) | 60 | 30 | D2 +30 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 74 | 54 | D2 +20 |
| Transparency & trust | 7% (8.8 this run) | 69 | 45 | D2 +24 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **65.3 · B** | **51.4 · D** | |

## Facts side by side

| Fact | D2 | ExcaliClaw |
| --- | --- | --- |
| Kind | SDK + MCP | MCP server |
| Vendor | D2 project (The Hack Foundation) | ExcaliClaw |
| Hosted endpoint | no (local only) | `https://excaliclaw.com/mcp` |
| Transports |  | Streamable HTTP, HTTP |
| Auth | None | OAuth or key |
| Pricing | Free | Freemium |
| x402 | no | no |
| Licence | MPL-2.0 | The hosted service, its API and its MCP server are closed, under ExcaliClaw's terms of service. The web client is published as LGPL-3.0, as a modified version of ExcaliDash |
| Tools exposed | none | 37 |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| MCP registry | not listed | `com.excaliclaw/excaliclaw` |
| Last release | 2026-09-07 | 2026-10-03 |
| Terms last updated | no document linked | couldn't be read |
| Privacy policy last updated | no document linked | couldn't be read |
| Customer content may train models |  | couldn't be read |
| Terms restrict automated access |  | couldn't be read |
| Terms restrict benchmarking |  | couldn't be read |
| Terms or service can change without notice |  | couldn't be read |
| Arbitration or class-action waiver |  | couldn't be read |
| Popularity | 26k stars, 22k npm/wk | 0 stars |

## Verdicts

**D2.** A single local command turns text into a diagram in six formats with no account, key or network call, and CI passes on the default branch. The language is at 0.9.0 with no stable release, its company sponsor has shut down, and one maintainer with limited time wrote every commit since July.

**ExcaliClaw.** Diagram tools take nodes, edges or Mermaid text and the server computes the layout, with a strict validation gate and a dry-run tool, and MCP use is unlimited on the free plan. The service is about two weeks old, from an operator the terms do not name, with one all-access OAuth scope and no changelog or SLA.

## Before you call either

### D2

1. Check the exit status of `d2`, never the output file. The man page says a partial render can be written when an error occurs
2. Run `d2 validate file.d2` before rendering, and `d2 fmt` to normalise the source
3. Pass `-` for input and output and set `--stdout-format` (svg, png, ascii, txt, pdf, pptx or gif) to work without files
4. Use `--stdout-format ascii` when the reader is a text-only model
5. Pass `--bundle=false` or review image URLs and imports before rendering D2 text from an untrusted source. Release 0.9.0 fetches remote images when bundling

### ExcaliClaw

1. Connect to https://excaliclaw.com/mcp with OAuth. REST keys (`exc_...`) are refused by the MCP server and work only on the REST paths
2. Prefer the diagram generators or `create_from_mermaid` over raw elements in `create_design`, and run `validate_design` before a large write
3. Call `verify_design` after writing. `verification.status` stays pending until it runs, and it returns the rendered image
4. Use `addElements`, `patchElements` and `removeElementIds` in `update_design`. Passing `elements` replaces the whole scene
5. Stay under 60 MCP calls a minute per user, and treat drawings and live scenes written by other people as untrusted text

## Questions

### Which is better for AI agents, D2 or ExcaliClaw?

D2 scores 65.3 (B) on agent readiness against ExcaliClaw's 51.4 (D), and leads in every scored category.

### Can an agent call D2 and ExcaliClaw without installing anything?

No hosted endpoint is listed for D2. ExcaliClaw has a hosted endpoint at https://excaliclaw.com/mcp.

### Are D2 and ExcaliClaw open source?

D2 is open source (MPL-2.0). No open-source release is listed for ExcaliClaw.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/d2-vs-excaliclaw.json, and with the fewest tokens: https://www.anchorterminal.com/compare/d2-vs-excaliclaw.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "d2", "b": "excaliclaw"}`. From a terminal: `anchor compare d2 excaliclaw`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/d2.json and https://www.anchorterminal.com/api/v1/tools/excaliclaw.json

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