ExcaliClaw

ExcaliClaw is a collaborative workspace for hand-drawn diagrams, with a hosted MCP server.

CommunityOnlineNo sign-inGlobalFreeCan modify data

What it can do

  • List Designs: List drawings (designs), optionally filtered by collection. Each result includes a `url` — share it so the user can open the drawing directly.
  • Get Design: Fetch a single drawing by id. By default the result is COMPACT (cheaper and faster for you): elements without internal noise fields, a minimal appState and only the ids of embedded images.
  • Export Design: Export a drawing as an image you can look at or hand to the user: format "png" (returned as an image) or "svg" (returned as SVG text). Rendered on the server from the saved scene in Exc

What data it sees

Do you need an account

No: the server works without sign-in

ExcaliClaw is a collaborative workspace for hand-drawn diagrams, with a hosted MCP server. Connect it once with OAuth (no API key) and your AI agent can create flowcharts, architecture diagrams and entity-relationship diagrams, add sticky notes, organize drawings into collections and export them as PNG or SVG. The server computes the layout, so shapes never overlap. Agents can also read and edit a drawing that people have open right now, in real time.

What your agent can do

  • Create diagrams: create_flow_diagram (flowcharts and architecture diagrams, with optional hand-drawn icons), create_er_diagram (entity-relationship diagrams) and add_sticky_note.
  • Manage drawings: list_designs, get_design, create_design, update_design, delete_design.
  • Organize: list_collections, create_collection, move_designs_to_collection.
  • Export: export_design returns a PNG or SVG, with a public URL if you want one.
  • Work live: get_live_scene, apply_live_scene_change, wait_for_scene_change.
  • Reuse components: list_library_components, get_library_component, save_library_component.

Connect

Server URL: https://excaliclaw.com/mcp (Streamable HTTP, OAuth sign-in, no API key).

  • Claude Code: claude mcp add excaliclaw --transport http https://excaliclaw.com/mcp
  • Cursor: Settings > MCP > Add new MCP server, then { "url": "https://excaliclaw.com/mcp" }
  • VS Code (Copilot Chat): .vscode/mcp.json with { "type": "http", "url": "https://excaliclaw.com/mcp" }
  • Claude Desktop / Claude.ai: Settings > Connectors > Add custom connector, paste the URL.
  • Codex CLI: codex mcp add excaliclaw --url https://excaliclaw.com/mcp

You sign in with your ExcaliClaw account the first time. Free to start; MCP usage is unlimited on every plan.

Links

How to connect

How to connect ExcaliClaw to Claude

The server address to paste into Claude settings:

https://excaliclaw--mbella19.run.tools

  1. Open Claude (claude.ai or the desktop app).
  2. Go to Settings → Connectors.
  3. Click Add custom connector.
  4. Paste the server address copied below into Remote MCP server URL and click Add.
  5. In a chat, click + → Connectors and switch the new connector on.

Custom connectors are available on Free, Pro, Max, Team and Enterprise plans (Free is limited to one). On Team and Enterprise an organization Owner adds the connector first under Organization settings → Connectors.

Authorization

After you click Add, a sign-in window for the service opens. Sign in with your own account and approve access. Claude never sees your password.

How to connect ExcaliClaw to ChatGPT

The server address to paste into ChatGPT settings:

https://excaliclaw--mbella19.run.tools

  1. Open ChatGPT in a browser (chatgpt.com). A Plus, Pro, Business, Enterprise or Edu plan is required.
  2. Turn on developer mode once: Settings → Apps → Advanced settings → Developer mode.
  3. Open Settings → Connectors and click Create.
  4. Fill in the form: Name (anything), Description (one line about what the service does), MCP server URL (copy it below).
  5. Under Authentication choose OAuth if the service requires sign-in, otherwise None. Click Create.
  6. In a new chat open + → Apps/Connectors and enable the connector.

OpenAI has renamed this section before (Connectors → Apps/Plugins). If the label differs, search settings for "developer mode". On Business/Enterprise workspaces an admin must allow custom connectors first.

Authorization

On first use ChatGPT opens the service's sign-in window. Sign in and approve access.

How to connect ExcaliClaw to Cursor

The server address to paste into Cursor settings:

https://excaliclaw--mbella19.run.tools

Fastest: click Open in Cursor below and confirm the prompt.

Manually:

  1. In Cursor open Settings → Cursor Settings → MCP and click Add new global MCP server.
  2. Paste the JSON copied below into ~/.cursor/mcp.json (per project: .cursor/mcp.json in the repo root).
  3. Save the file. The server appears in the MCP list; authorize it there if asked.

Authorization

If the service needs sign-in, an authorize button appears next to the server in the MCP list.

Server tool list (18)

Raw names from tools/list. Only developers need these.

list_designsList drawings (designs), optionally filtered by collection. Each result includes a `url` — share it so the user can open the drawing directly.
get_designFetch a single drawing by id. By default the result is COMPACT (cheaper and faster for you): elements without internal noise fields, a minimal appState and only the ids of embedded images. Pass includeFiles:true to also get image data, or compact:false for the raw full scene. The result includes a `url` — share it so the user can open the drawing directly.
export_designExport a drawing as an image you can look at or hand to the user: format "png" (returned as an image) or "svg" (returned as SVG text). Rendered on the server from the saved scene in Excalidraw's hand-drawn palette (clean strokes, no sketchy wobble). Use it to check how a diagram you built or edited looks. The result includes the editor `url` and a public CDN URL (no login needed, cached at the edge, new URL whenever the drawing changes) you can paste into an <img>, Markdown or a chat. Pass urlOnly:true to get just that link instead of the image body — far cheaper in tokens.
create_designCreate a new drawing from raw Excalidraw elements (or blank if omitted). Prefer create_er_diagram or create_flow_diagram instead when the drawing is an entity-relationship diagram or a flowchart/architecture diagram — those compute every element's position server-side, which is far more reliable than hand-placing x/y coordinates for many shapes yourself here. The result includes a `url` — always share it so the user can open what you made.
update_designUpdate an existing drawing: rename it, move it to another collection (pass collectionId, or null to move it to Unorganized), and/or change its scene. To change the scene PREFER the partial operations addElements / patchElements / removeElementIds: you only send what changes instead of the whole scene, which is much faster and cheaper. `elements` replaces the whole scene and cannot be combined with them. The result includes a `url` — share it so the user can open the drawing directly.
delete_designDelete a drawing by id.
move_designs_to_collectionMove several drawings to a collection (or to Unorganized with collectionId=null) in a single call. Prefer this over calling update_design once per drawing when moving more than one at a time. Returns a per-id success/error result.
list_collectionsList collections (folders) owned by the authenticated user.
create_collectionCreate a new collection.
list_library_componentsList the user's saved/reusable component shelf (their Excalidraw library — items they saved with "Add to library", or a community icon set they imported). Each entry's `name` is a best-effort guess (the first short text label found inside it) — use it as the `icon` value in create_flow_diagram's nodes, or with get_library_component, to reuse the EXACT same saved shapes instead of guessing a logo's geometry from scratch.
get_library_componentFetch a saved library component's raw Excalidraw elements by name (from list_library_components) — copy these into create_design's elements (translating x/y as needed) to reuse a user's exact saved shape instead of drawing your own approximation.
save_library_componentSave a set of Excalidraw elements as a named, reusable component in the user's library — e.g. after drawing a good logo/icon by hand, save it once under a clear name ("redis", "aws") so it (and every other agent) can reuse the EXACT same shape later via get_library_component or create_flow_diagram's `icon`, instead of redrawing an approximation each time. Saving again under an existing name overwrites it.
create_er_diagramCreate a classic Chen-notation entity-relationship diagram: entity boxes, each with its attributes drawn as ellipses fanned out above it, connected to related entities via relationship diamonds with cardinality labels (e.g. 1, N, 0..1) on each side. The server computes every coordinate — never guess positions yourself with create_design for this kind of diagram, an LLM placing a dozen-plus ellipses by hand reliably produces overlapping shapes and crossed lines. The result includes a `url` — always share it so the user can open what you made.
create_flow_diagramCreate a flowchart/architecture diagram: pass nodes and edges, the server lays out and generates the full scene. Cheaper than create_design's raw elements. Nodes can carry an `icon` (e.g. "react", "redis", "aws") placed above the node — if the name matches a component in the user's saved library (see list_library_components) that EXACT saved shape is reused; otherwise a small built-in hand-drawn sketch is used as a fallback. Unknown icon names are silently skipped. The result includes a `url` — always share it so the user can open what you made.
add_sticky_noteAdd a sticky note (a colored box with a short note written on it, like a physical Post-it) to an existing drawing. Appends to the saved scene — if the drawing is open live in a browser right now, that tab won't show it until it reloads or re-saves (same as update_design). The result includes a `url` — share it so the user can open the drawing directly.
get_live_sceneRead the CURRENT live state of a drawing's canvas, including edits connected browser tabs have made that haven't been saved yet — not just the last-saved snapshot get_design returns. The result is tagged with a `revision` counter; pass it to wait_for_scene_change to be notified next time it advances. Compact by default (no internal noise fields, image ids only); pass includeFiles:true for image data or compact:false for the raw snapshot.
wait_for_scene_changeBounded long-poll (up to ~25s) that resolves as soon as the drawing's live scene changes past `sinceRevision`, or on timeout — whichever comes first. Use this in a loop (feeding back the returned `revision`) to react to a human's edits as they happen, without tight polling. Returns immediately with noActiveClients:true if nobody is currently connected to the drawing (nothing can change if no one is there to change it).
apply_live_scene_changeAdd or update elements on a drawing's LIVE canvas — broadcast through the same real-time channel human browser tabs use, so every connected tab sees it appear immediately, exactly as if another human had drawn it. Requires edit (not just view) access to the drawing. Prefer create_er_diagram/create_flow_diagram's element shapes, or get_live_scene's current elements, as a reference for well-formed Excalidraw element objects.