# Diagramming APIs and diagram-as-code for AI agents

> 10 diagramming listings ranked by the Anchor benchmark. Leader Miro API + MCP (B). Tools an agent can use to draw architecture, flow and sequence diagrams, through a REST API, an MCP server, an SDK or a diagram-as-code format. Compared on how the diagram is described, whether it stays editable, export formats and what it costs.

- Canonical: https://www.anchorterminal.com/categories/diagramming
- Markdown: https://www.anchorterminal.com/categories/diagramming.md (~2,850 tokens)
- Slim: https://www.anchorterminal.com/categories/diagramming.min.md (~530 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/categories/diagramming.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: 2026-10-04

Tools an agent can use to draw architecture, flow and sequence diagrams, through a REST API, an MCP server, an SDK or a diagram-as-code format. Compared on how the diagram is described, whether it stays editable, export formats and what it costs.

- Tools ranked: 10 · agent-ready (BB or better): 0 · accept x402: 0 · hosted endpoints: 10 · desk reviews by the panel: 20
- JSON: https://www.anchorterminal.com/api/v1/tools.json (list) · https://www.anchorterminal.com/api/v1/rankings.json (ranked) · https://www.anchorterminal.com/api/v1/x402.json (payable) · https://www.anchorterminal.com/api/v1/capabilities.json (by capability)
- Grades run AA, A, BB, B, C, D, E, F · methodology: https://www.anchorterminal.com/benchmark/

- Capabilities in this category: diagram.create, diagram.as-code, diagram.edit, diagram.export, diagram.architecture
- https://letme.dev/diagram.create picks the top-graded tool in this list and says how to call it direct; calling through letme comes later (https://www.anchorterminal.com/letme/index.md)

## Ranking

| # | Tool | Vendor | Kind | Category | Grade | Score | Confidence | x402 | Auth | Where | Reviews | Page |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 175 | Miro API + MCP | Miro | HTTP API | Design | B | 65.3 | medium | no | OAuth | hosted | 4/5 (2) | https://www.anchorterminal.com/tools/miro.md |
| 219 | draw.io + MCP | draw.io | MCP server | Diagrams | B | 62.4 | medium | no | None | hosted + local | 4/5 (2) | https://www.anchorterminal.com/tools/drawio.md |
| 236 | tldraw SDK + MCP | tldraw | SDK + MCP | Diagrams | C | 61 | medium | no | None | hosted | 3/5 (2) | https://www.anchorterminal.com/tools/tldraw.md |
| 238 | Lucid API + MCP | Lucid Software | HTTP API | Diagrams | C | 60.9 | medium | no | OAuth or key | hosted | 3/5 (2) | https://www.anchorterminal.com/tools/lucid.md |
| 252 | Structurizr + MCP | Structurizr | HTTP API | Diagrams | C | 60.2 | medium | no | OAuth or key | hosted | 3/5 (2) | https://www.anchorterminal.com/tools/structurizr.md |
| 255 | Diagrams.so API + MCP | Diagrams.so (RedHold LLC) | HTTP API | Diagrams | C | 60.1 | medium | no | OAuth or key | hosted + local | 4/5 (2) | https://www.anchorterminal.com/tools/diagrams-so.md |
| 341 | Whimsical MCP | Whimsical | MCP server | Diagrams | D | 52.7 | medium | no | OAuth | hosted | 3/5 (2) | https://www.anchorterminal.com/tools/whimsical.md |
| 427 | Eraser API + MCP | Eraser | HTTP API | Diagrams | E | 38.7 | medium | no | OAuth or key | hosted + local | 3/5 (2) | https://www.anchorterminal.com/tools/eraser.md |
| 432 | Cloudviz API | Cloudviz | HTTP API | Diagrams | F | 37.9 | medium | no | API key | hosted | 2.5/5 (2) | https://www.anchorterminal.com/tools/cloudviz.md |
| 442 | Mermaid Chart MCP | Mermaid Chart | MCP server | Diagrams | F | 31.7 | medium | no | OAuth or key | hosted | 2.5/5 (2) | https://www.anchorterminal.com/tools/mermaid-chart.md |

Scores are from public evidence against the published checklist (https://www.anchorterminal.com/benchmark/), with Performance and Task success pending. p95 latency and context cost come from our probes, which haven't run yet.

## Summaries

### 175. Miro API + MCP, B (65.3)

Miro's REST API v2 reads and writes boards and board items (sticky notes, shapes, connectors, frames, cards, text, images, documents), tags and members, so an agent can lay out diagrams as well as notes. REST creates shapes, connectors and frames, so flowcharts and architecture sketches can be drawn directly. Legacy MCP board tools were removed nine days after the deprecation notice.

- Page: https://www.anchorterminal.com/tools/miro · Markdown: https://www.anchorterminal.com/tools/miro.md · JSON: https://www.anchorterminal.com/api/v1/tools/miro.json
- Capabilities: design.files, design.canvas, design.comments, diagram.create, diagram.edit · endpoint: `https://api.miro.com/v2`

### 219. draw.io + MCP, B (62.4)

The open-source diagram editor (also diagrams.net) with an official MCP server. Free, keyless and Apache 2.0, with a Docker image for self-hosting. Tool descriptions embed a 34.5 KB XML reference and a 14 KB Mermaid reference, roughly 13,000 tokens.

- Page: https://www.anchorterminal.com/tools/drawio · Markdown: https://www.anchorterminal.com/tools/drawio.md · JSON: https://www.anchorterminal.com/api/v1/tools/drawio.json
- Capabilities: diagram.create, diagram.as-code, diagram.edit, diagram.export, diagram.architecture · endpoint: `https://mcp.draw.io/mcp`

### 236. tldraw SDK + MCP, C (61)

A React infinite-canvas SDK that an agent can drive through the editor API, creating, reading and changing shapes, turning Mermaid into shapes and exporting images. Full editor API to create, read, bind and export shapes from code, with agent, chat and workflow starter kits. Source-available, and commercial prices aren't published.

- Page: https://www.anchorterminal.com/tools/tldraw · Markdown: https://www.anchorterminal.com/tools/tldraw.md · JSON: https://www.anchorterminal.com/api/v1/tools/tldraw.json
- Capabilities: diagram.create, diagram.as-code, diagram.edit, diagram.export · endpoint: `https://tldraw-mcp-app.tldraw.workers.dev/mcp`

### 238. Lucid API + MCP, C (60.9)

REST API and hosted MCP server for creating, reading and managing Lucidchart and Lucidspark diagrams. OAuth 2.0 scopes with `:readonly` variants, and audit log endpoints in the REST API. No public changelog for the API or the MCP server.

- Page: https://www.anchorterminal.com/tools/lucid · Markdown: https://www.anchorterminal.com/tools/lucid.md · JSON: https://www.anchorterminal.com/api/v1/tools/lucid.json
- Capabilities: diagram.create, diagram.as-code, diagram.edit, diagram.export, design.files, design.canvas, design.comments · endpoint: `https://api.lucid.co`

### 252. Structurizr + MCP, C (60.2)

Diagram-as-code tool for software architecture using the C4 model. One model can generate several C4 architecture views. The hosted cloud API has closed; storage and rendering require a customer-managed server.

- Page: https://www.anchorterminal.com/tools/structurizr · Markdown: https://www.anchorterminal.com/tools/structurizr.md · JSON: https://www.anchorterminal.com/api/v1/tools/structurizr.json
- Capabilities: diagram.create, diagram.as-code, diagram.edit, diagram.export, diagram.architecture · endpoint: `https://mcp.structurizr.com/mcp`

### 255. Diagrams.so API + MCP, C (60.1)

Turns a plain-English description into an editable draw.io diagram with cloud icons (AWS, Azure, GCP, OCI, Kubernetes). 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.

- Page: https://www.anchorterminal.com/tools/diagrams-so · Markdown: https://www.anchorterminal.com/tools/diagrams-so.md · JSON: https://www.anchorterminal.com/api/v1/tools/diagrams-so.json
- Capabilities: diagram.create, diagram.edit, diagram.export, diagram.architecture · endpoint: `https://api.diagrams.so/api/v2`

### 341. Whimsical MCP, D (52.7)

Official hosted MCP server for the Whimsical workspace. OAuth 2.1 with PKCE and separate read and write scopes. No API keys, so it can't run headless or in CI.

- Page: https://www.anchorterminal.com/tools/whimsical · Markdown: https://www.anchorterminal.com/tools/whimsical.md · JSON: https://www.anchorterminal.com/api/v1/tools/whimsical.json
- Capabilities: diagram.create, diagram.edit, diagram.export · endpoint: `https://mcp.whimsical.com/mcp`

### 427. Eraser API + MCP, E (38.7)

Docs and diagrams workspace for engineers. Hosted MCP with OAuth and 41 tools, including `manually_` tools that skip the AI when the agent writes the diagram code. No status page, rate limits, SLA or changelog.

- Page: https://www.anchorterminal.com/tools/eraser · Markdown: https://www.anchorterminal.com/tools/eraser.md · JSON: https://www.anchorterminal.com/api/v1/tools/eraser.json
- Capabilities: diagram.create, diagram.as-code, diagram.edit, diagram.export, diagram.architecture · endpoint: `https://app.eraser.io/api`

### 432. Cloudviz API, F (37.9)

Generates AWS architecture diagrams from a live account. Diagrams come from the live AWS account through a read-only cross-account role with a per-customer external ID. AWS only, and API access starts at the $49 a month Team plan.

- Page: https://www.anchorterminal.com/tools/cloudviz · Markdown: https://www.anchorterminal.com/tools/cloudviz.md · JSON: https://www.anchorterminal.com/api/v1/tools/cloudviz.json
- Capabilities: diagram.create, diagram.export, diagram.architecture · endpoint: `https://api.cloudviz.io`

### 442. Mermaid Chart MCP, F (31.7)

Hosted MCP server for Mermaid diagrams from mermaid.ai. Validation and rendering work with no account or key. Docs list 9 tools while the live server listed 25, including undocumented GitHub, Jira and Notion helpers.

- Page: https://www.anchorterminal.com/tools/mermaid-chart · Markdown: https://www.anchorterminal.com/tools/mermaid-chart.md · JSON: https://www.anchorterminal.com/api/v1/tools/mermaid-chart.json
- Capabilities: diagram.create, diagram.as-code, diagram.edit, diagram.export · endpoint: `https://mcp.mermaid.ai/mcp`

## Indexed, not reviewed (6)

Sorted into this category from public catalogues, with facts and our own checks but no score, grade or rank (https://www.anchorterminal.com/indexed/index.md).

| Listing | Kind | What it does | Why it's here |
| --- | --- | --- | --- |
| [chartforge](https://www.anchorterminal.com/tools/chartforgeai-chartforge.md) | MCP server | MCP server for ChartForge — generate stunning charts and diagrams from natural language | vendor's own |
| [DiagramZu](https://www.anchorterminal.com/tools/diagramzu-mcp.md) | MCP server | Let Claude, Cursor, or ChatGPT author Mermaid diagrams your team can read and share. | vendor's own |
| [DrillFlow](https://www.anchorterminal.com/tools/drillflow-mcp.md) | MCP server | Publish drill-down diagrams from an agent; every Mermaid subgraph becomes a level you enter. | vendor's own |
| [Flowgraf](https://www.anchorterminal.com/tools/flowgraf.md) | MCP server | Create and edit architecture diagrams from your AI agent; get an SVG and a live editable canvas. | vendor's own |
| [noddle draw](https://www.anchorterminal.com/tools/noddle-draw.md) | MCP server | Read, create and edit open-source noddle draw diagram boards, browse versions and comment. | vendor's own |
| [vgraph-mcp](https://www.anchorterminal.com/tools/vithanco-vgraph-mcp.md) | MCP server | Concept Maps, IBIS, Causal Loop Diagrams and Timelines as images. Runs locally via WebAssembly. | vendor's own |