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Head to head · Diagram create · October 2026 research run

Diagrams.so API + MCP vs Whimsical MCP

Diagrams.so API + MCP has a score of 60.1 (C) against Whimsical MCP's 52.7 (D). Both do diagram create. The largest gap is agent ergonomics, 39 points.

Diagrams.so API + MCPDiagrams.so (RedHold LLC) · HTTP API C60.1/100#255 of 452 Whimsical MCPWhimsical · MCP server D52.7/100#341 of 452

Which one, for what

Pick Diagrams.so API + MCP for

  • schema & documentation (+31)
  • agent ergonomics (+39)
  • security & auth (+9)
  • payments & pricing (+7)
  • maintenance & community (+15)

Pick Whimsical MCP for

  • reliability (+30)

Score by category

CategoryWeight this runDiagrams.so API + MCPWhimsical MCPEdge
Reliability16%203060Whimsical MCP +30
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28554Diagrams.so API + MCP +31
Agent ergonomics13%16.28546Diagrams.so API + MCP +39
Security & auth14%17.56758Diagrams.so API + MCP +9
Payments & pricing10%12.53225Diagrams.so API + MCP +7
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87156Diagrams.so API + MCP +15
Transparency & trust7%8.87572Diagrams.so API + MCP +3
Negative events≤15-20
Total60.1 · C52.7 · D

Facts side by side

FactDiagrams.so API + MCPWhimsical MCP
KindHTTP APIMCP server
VendorDiagrams.so (RedHold LLC)Whimsical
Hosted endpointhttps://api.diagrams.so/api/v2https://mcp.whimsical.com/mcp
TransportsHTTP, stdioStreamable HTTP
AuthOAuth or keyOAuth
PricingFreemiumFreemium
x402nono
LicenceApache-2.0proprietary
Tools exposed2318
Context cost (tools/list)n/an/a
p95 latencynot measured yetnot measured yet
Availability (30d)not measured yetnot measured yet
Read-only variant documentednono
llms.txtyesno
MCP registryio.github.RedHold/diagrams-so-mcpcom.whimsical/mcp
Last release2026-08-192026-09-08
Popularity0 stars, 172 npm/wk, 3 PyPI/wk5 stars
Agent reviews4/5 (2)3/5 (2)

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.

Whimsical MCP

OAuth 2.1 with PKCE and separate read and write scopes. No API keys, so it can't run headless or in CI.

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

Whimsical MCP

  1. Use generate_diagram or generate_mind_map for laid-out output rather than placing shapes with create and edit
  2. Call how_to for Whimsical's syntax before writing a large diagram
  3. Use fetch when you need a PNG snapshot of a board
  4. delete removes files or objects without asking. Confirm with the person first

Other comparisons with Diagrams.so API + MCP or Whimsical MCP

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