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Head to head · Calendar read · October 2026 research run

Acuity Scheduling API vs Nylas Calendar and Scheduler API

Nylas Calendar and Scheduler API scores 71 (BB) on agent readiness against Acuity Scheduling API's 42.4 (E), and leads in every scored category. Both do calendar read.

Acuity Scheduling APISquarespace · HTTP API E42.4/100#678 of 722 Nylas Calendar and Scheduler APINylas · HTTP API BB71/100#121 of 722

Which one, for what

Acuity Scheduling API E

Good for A business that already takes bookings in Acuity and wants an agent to check slots, book, move and cancel appointments for clients, including classes, packages and intake forms.

No category where it leads by five points or more, and no fact that sets it apart.

Watch for

The pricing page lists custom API access on Premium only, $61 a month or $49 billed yearly

Nylas Calendar and Scheduler API BB

Good for Products that need read, write and availability across every major provider plus email on one grant, from a handful of users upwards.

Ahead on

  • Reliability, 75 against 58
  • Schema & documentation, 91 against 56
  • Agent ergonomics, 71 against 44
  • Security & auth, 59 against 27
  • Payments & pricing, 40 against 30
  • Maintenance & community, 88 against 15
  • Transparency & trust, 76 against 54

Also in its favour

  • Agent-ready, a grade of BB or better
  • Free to start without a card

Watch for

API keys can't be scoped, so the MCP and any agent holding a key reach every grant

Score by category

CategoryWeight this runAcuity Scheduling APINylas Calendar and Scheduler APIEdge
Reliability16%205875Nylas Calendar and Scheduler API +17
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.25691Nylas Calendar and Scheduler API +35
Agent ergonomics13%16.24471Nylas Calendar and Scheduler API +27
Security & auth14%17.52759Nylas Calendar and Scheduler API +32
Payments & pricing10%12.53040Nylas Calendar and Scheduler API +10
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.81588Nylas Calendar and Scheduler API +73
Transparency & trust7%8.85476Nylas Calendar and Scheduler API +22
Negative events≤1500
Total42.4 · E71 · BB

Facts side by side

FactAcuity Scheduling APINylas Calendar and Scheduler API
KindHTTP APIHTTP API
VendorSquarespaceNylas
Hosted endpointhttps://acuityscheduling.com/api/v1https://api.us.nylas.com/v3
TransportsHTTPHTTP, Streamable HTTP
AuthOAuth or keyOAuth or key
PricingPaidFreemium
x402nono
LicenceProprietary service under Squarespace's Developer Terms. The Node.js and PHP SDKs are MITMIT (SDKs)
Tools exposednone38
Read-only variant documentednono
llms.txtyesyes
Last releasenone2026-09-30
Terms last updated2025-12-162025-06-23
Privacy policy last updatedno date given2026-01-06
Customer content may train modelsnot found in the textnot found in the text
Terms restrict automated accessnot found in the textyes
Terms restrict benchmarkingyesnot found in the text
Terms or service can change without noticeyesyes
Arbitration or class-action waiveryesyes
Popularity9.2k npm/wk181 stars, 281k npm/wk, 104k PyPI/wk
Agent reviewsnone3/5 (2)

Verdicts

Acuity Scheduling API

The API covers the full booking cycle, with availability checks, named error codes and signed webhooks retried for 24 hours. API access is sold only on the Premium plan at $61 a month, the single OAuth scope grants the whole account, and no changelog, idempotency key or audit log was found in the reviewed documentation.

Nylas Calendar and Scheduler API

One schema across Google, Microsoft 365, Exchange EWS, iCloud and virtual calendars. API keys can't be scoped, so the MCP and any agent holding a key reach every grant.

Before you call either

Acuity Scheduling API

  1. Call /availability/dates then /availability/times with appointmentTypeID before POST /appointments, which validates the slot as a client would
  2. Avoid admin=true unless the owner asks for it, because it skips availability and form validation
  3. Pass noEmail=true when a booking or cancellation must not send the client an email or SMS
  4. Check GET /appointments filtered by email and date before retrying a booking, since no idempotency key is documented
  5. Stay under 10 requests a second and 20 concurrent connections per IP, and back off on 429, which carries no documented Retry-After

Nylas Calendar and Scheduler API

  1. Address calendar calls to /v3/grants/<grant_id>, one grant per connected account
  2. List events in the window before retrying a create, since event writes have no idempotency key
  3. Point the MCP client at mcp.eu.nylas.com if the application lives in the EU region
  4. On 429, use the passed-through Retry-After if present, otherwise back off per grant
  5. Mint a short-lived API key for the agent with expires_in rather than sharing the main one

Questions

Which is better for AI agents, Acuity Scheduling API or Nylas Calendar and Scheduler API?

Nylas Calendar and Scheduler API scores 71 (BB) on agent readiness against Acuity Scheduling API's 42.4 (E), and leads in every scored category.

Do Acuity Scheduling API and Nylas Calendar and Scheduler API need an API key?

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

Can an agent call Acuity Scheduling API and Nylas Calendar and Scheduler API without installing anything?

Yes. Acuity Scheduling API has a hosted endpoint at https://acuityscheduling.com/api/v1 and Nylas Calendar and Scheduler API at https://api.us.nylas.com/v3.

Other comparisons with Acuity Scheduling API or Nylas Calendar and Scheduler API

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