# Excalidraw vs PlantUML

> PlantUML scores 66.9 (B) to Excalidraw's 54.5 (C) for diagram creation. Prices, MCP, x402, uptime and agent notes side by side.

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

PlantUML scores 66.9 (B) on agent readiness against Excalidraw's 54.5 (C), and leads in 5 of 7 scored categories. Excalidraw leads on security & auth. Both do diagram creation.

- Excalidraw: grade C, 54.5/100, rank #683 of 950. Markdown https://www.anchorterminal.com/tools/excalidraw.md · JSON https://www.anchorterminal.com/api/v1/tools/excalidraw.json
- PlantUML: grade B, 66.9/100, rank #270 of 950. Markdown https://www.anchorterminal.com/tools/plantuml.md · JSON https://www.anchorterminal.com/api/v1/tools/plantuml.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

### Excalidraw (C)

Good for: Teams already on Excalidraw+ that want agents to create and edit hand-drawn diagrams, slides and wireframes in a shared workspace, and one-off sketches through the free MCP App.

Ahead on:
- Security & auth, 73 against 50

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

Watch for: The API and MCP server are in public beta. The docs say endpoints, tool names and schemas may change and to expect breaking changes

### PlantUML (B)

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 50
- Agent ergonomics, 78 against 58
- Payments & pricing, 60 against 35
- Maintenance & community, 73 against 44
- Transparency & trust, 73 against 63

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

Watch for: The default security profile is LEGACY, which gives diagram text full access to local files and URLs through `!include`. The docs say it will be removed, with no date


## Score by category

| Category | Weight | Excalidraw | PlantUML | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 50 | 83 | PlantUML +33 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 65 | 65 | even |
| Agent ergonomics | 13% (16.2 this run) | 58 | 78 | PlantUML +20 |
| Security & auth | 14% (17.5 this run) | 73 | 50 | Excalidraw +23 |
| Payments & pricing | 10% (12.5 this run) | 35 | 60 | PlantUML +25 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 44 | 73 | PlantUML +29 |
| Transparency & trust | 7% (8.8 this run) | 63 | 73 | PlantUML +10 |
| Negative events | ≤15 | -2 | -2 | |
| **Total** | | **54.5 · C** | **66.9 · B** | |

## Facts side by side

| Fact | Excalidraw | PlantUML |
| --- | --- | --- |
| Kind | HTTP API | SDK + MCP |
| Vendor | Excalidraw s.r.o. | PlantUML project (Arnaud Roques) |
| Hosted endpoint | `https://api.excalidraw.com/api/v1/mcp` | no (local only) |
| Transports | HTTP, Streamable HTTP |  |
| Auth | API key | None |
| Pricing | Freemium | Free |
| x402 | no | no |
| Licence | Excalidraw+ is a proprietary service under Excalidraw's terms of use. The editor and the MCP App on GitHub are MIT | GPL-3.0-or-later |
| Tools exposed | 37 | none |
| Read-only variant documented | no | no |
| llms.txt | yes | no |
| Last release | 2026-09-01 | 2026-09-05 |
| Terms last updated | no date given | no document linked |
| Privacy policy last updated | 2021-04-29 | no document linked |
| Customer content may train models | not found in the text |  |
| Terms restrict automated access | yes |  |
| Terms restrict benchmarking | not found in the text |  |
| Terms or service can change without notice | yes |  |
| Arbitration or class-action waiver | yes |  |
| Popularity | 134k stars, 676k npm/wk | 13k stars, 207 npm/wk |

## Verdicts

**Excalidraw.** Excalidraw+ keys carry read or full permission, route restrictions and an expiry, and the MCP server shows a key only the tools its routes allow. The API and MCP server are in public beta with breaking changes expected, sit behind the $6 Plus plan, and have no published OpenAPI file, SDK or idempotency keys.

**PlantUML.** One Java command reads diagram text from stdin and writes PNG, SVG, PDF or ASCII with no account, and CI passed on the last eight pushes. The default security profile lets diagram text read any local file and fetch any URL, and the documentation still lists chronology diagrams that release 1.2026.2 switched off.

## Before you call either

### Excalidraw

1. Send `Authorization: Bearer <API_KEY>` to https://api.excalidraw.com/api/v1. For MCP, use `POST /api/v1/mcp` only. The server is stateless and answers 405 to other methods
2. Use a personal key to reach the owner's private collection with the collection ID `private`. A workspace admin must enable personal keys first
3. Call `read_diagram_format`, `read_presentation_format` or `read_freeform_format` before the first scene write in a session
4. Write with `edit_scene_content` and bind arrows through `startBinding` and `endBinding` with `tempId` references. `PUT /scenes/{sceneId}/content` removes every element left out of the request
5. Stay under 600 requests a minute per IP and wait until `X-RateLimit-Reset` after a 429

### PlantUML

1. Set `PLANTUML_SECURITY_PROFILE` to `SANDBOX` or `ALLOWLIST` before rendering text from an untrusted source. The default profile lets `!include` read local files and fetch URLs
2. Run `java -jar plantuml.jar --check-syntax` with `-stdrpt` first and read the exit status. Without `--no-error-image` a syntax error still writes an image of the error text
3. Pass `-pipe` with `--svg`, `--txt` or `--utxt` to work without files. `--txt` output suits a text-only model
4. Start the local server as `-picoweb:8080:127.0.0.1`. Without the bind address it listens on every interface
5. Use `npx -y @plantuml/mcp-js` when no Java runtime is present. It renders SVG only, so use the jar for PNG or PDF

## Questions

### Which is better for AI agents, Excalidraw or PlantUML?

PlantUML scores 66.9 (B) on agent readiness against Excalidraw's 54.5 (C), and leads in 5 of 7 scored categories. Excalidraw leads on security & auth.

### Can an agent call Excalidraw and PlantUML without installing anything?

Excalidraw has a hosted endpoint at https://api.excalidraw.com/api/v1/mcp. No hosted endpoint is listed for PlantUML.

### Are Excalidraw and PlantUML open source?

Yes. Excalidraw is open source (Excalidraw+ is a proprietary service under Excalidraw's terms of use. The editor and the MCP App on GitHub are MIT). PlantUML is open source (GPL-3.0-or-later).


## For agents

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

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