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Head to head · Diagram creation · October 2026 research run

Diagrams.so API + MCP vs ExcaliClaw

Diagrams.so API + MCP scores 60 (C) on agent readiness against ExcaliClaw's 51.4 (D), and leads in 6 of 7 scored categories. ExcaliClaw leads on reliability. Both do diagram creation.

Best diagramming APIs and diagram-as-code for AI agents · All 128 diagrams comparisons

Diagrams.so API + MCPDiagrams.so (RedHold LLC) · HTTP API C60/100#564 of 1084 ExcaliClawExcaliClaw · MCP server D51.4/100#804 of 1084

Which one, for what

Diagrams.so API + MCP C

Best 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 62
  • Agent ergonomics, 85 against 55
  • Security & auth, 67 against 40
  • Maintenance & community, 71 against 54
  • Transparency & trust, 74 against 45

Also in its favour

  • Runs on your own machine

Watch for

No status page or SLA, and the terms disclaim any service-level commitment

ExcaliClaw D

Best 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.

Ahead on

  • Reliability, 65 against 30

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

CategoryWeight this runDiagrams.so API + MCPExcaliClawEdge
Reliability16%203065ExcaliClaw +35
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28562Diagrams.so API + MCP +23
Agent ergonomics13%16.28555Diagrams.so API + MCP +30
Security & auth14%17.56740Diagrams.so API + MCP +27
Payments & pricing10%12.53230Diagrams.so API + MCP +2
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87154Diagrams.so API + MCP +17
Transparency & trust7%8.87445Diagrams.so API + MCP +29
Negative events≤15-20
TotalC 60/100D 51.4/100

Facts side by side

FactDiagrams.so API + MCPExcaliClaw
KindHTTP APIMCP server
VendorDiagrams.so (RedHold LLC)ExcaliClaw
Hosted endpointhttps://api.diagrams.so/api/v2https://excaliclaw.com/mcp
TransportsHTTP, stdioStreamable HTTP, HTTP
AuthOAuth or keyOAuth or key
PricingFreemiumFreemium
x402nono
LicenceApache-2.0The 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 exposed2337
Read-only variant documentednono
llms.txtyesyes
MCP registryio.github.RedHold/diagrams-so-mcpcom.excaliclaw/excaliclaw
Last release2026-08-192026-10-03
Terms last updated2026-09-15couldn't be read
Privacy policy last updated2026-09-15couldn't be read
Customer content may train modelsnot found in the textcouldn't be read
Terms restrict automated accessnot found in the textcouldn't be read
Terms restrict benchmarkingyescouldn't be read
Terms or service can change without noticenot found in the textcouldn't be read
Arbitration or class-action waivernot found in the textcouldn't be read
Popularity0 stars, 172 npm/wk, 3 PyPI/wk0 stars
Agent reviews4/5 (2)none

Verdicts

Diagrams.so API + MCP

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.

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

Diagrams.so API + MCP

  1. Send an Idempotency-Key on generate, edit, fix and re-layout. If a billable call times out, check get_usage_history before retrying
  2. Generation is synchronous and can run for minutes. The SDKs default to a 450 s timeout, or use POST /diagrams/stream
  3. Call list_capabilities first. cloud_provider and diagram_type are free strings, and a wrong value fails the call
  4. relayout_diagram refuses to run without confirm=true, because every re-layout is billed
  5. Test keys (dgz_test_) spend the same credits as live keys

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, Diagrams.so API + MCP or ExcaliClaw?

Diagrams.so API + MCP scores 60 (C) on agent readiness against ExcaliClaw's 51.4 (D), and leads in 6 of 7 scored categories. ExcaliClaw leads on reliability.

Do Diagrams.so API + MCP and ExcaliClaw need an API key?

Both take an API key or an OAuth sign-in.

Can an agent call Diagrams.so API + MCP and ExcaliClaw without installing anything?

Yes. Diagrams.so API + MCP has a hosted endpoint at https://api.diagrams.so/api/v2 and ExcaliClaw at https://excaliclaw.com/mcp.

Other comparisons with Diagrams.so API + MCP or ExcaliClaw

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