Best of · Everyday APIs
Best calendar and scheduling APIs for AI agents
All 10 ranked calendar and scheduling APIs on the Anchor benchmark, with a pick for each need and where each one falls short. Scores come from public evidence, re-checked as vendors change.
- 10 ranked
- 2 agent-ready
- 10 hosted endpoints
- Updated 9 October 2026
Top three
Picks by need
Worked out from the scores, prices and facts, so they change when the research does.
Highest score overall
A, 80.6/100 on the benchmark.
Also Nylas Calendar and Scheduler API, BB, 71/100.
Schema & documentation
Nylas Calendar and Scheduler API BB
91/100 on schema & documentation, against 83 for the overall leader.
Maintenance & community
Nylas Calendar and Scheduler API BB
88/100 on maintenance & community, against 87 for the overall leader.
The shortlist
| # | Tool | Grade | Best for | Price | Where |
|---|---|---|---|---|---|
| 1 | Google Calendar API |
A 80.6 | An agent acting on Google Workspace or Gmail users' own calendars with tight scopes and no per-account fee. | Free | hosted |
| 2 | Nylas Calendar and Scheduler API Nylas |
BB 71 | Products that need read, write and availability across every major provider plus email on one grant, from a handful of users upwards. | $15 / mo | hosted |
| 3 | Calendly API + MCP Calendly |
B 68.3 | Best when the host already schedules through Calendly and the agent needs to find a slot and book or cancel it. | $10 / seat-mo | hosted |
| 4 | Microsoft Graph Calendar API Microsoft |
B 65.1 | Agents working inside Microsoft 365 tenants, especially when they need meeting-time suggestions across people and rooms. | Your plan | hosted |
| 5 | Cronofy API Cronofy |
B 64.2 | Products that schedule across many people and rooms with strict data residency, especially in the UK and EU. | $819 / mo | hosted |
| 6 | Cal.com API v2 + MCP Cal.com |
C 57.2 | An agent that books, reschedules and cancels meetings into a Cal.com user's event types, or routes leads with routing forms. | $12 / seat-mo | hosted and local |
| 7 | Zoom Scheduler API Zoom Communications, Inc. |
D 50.6 | An agent booking into a Zoom Scheduler user's or team's booking pages, with slot lookup, booking, cancellation and two webhooks. | $5.99 / seat-mo | hosted |
| 8 | Aurinko Calendar API Yoxel, Inc. |
E 45.6 | A product that connects many users' Google and Microsoft calendars and wants availability and booking at a low price per account. | Paid | hosted |
| 9 | Acuity Scheduling API Squarespace |
E 42.4 | 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. | $61 / mo | hosted |
| 10 | Apiroc Unified Calendar API Apiroc |
E 41.1 | A small product or an agent builder that needs read and write across Google, Microsoft and iCloud for tens to hundreds of accounts on a tight budget. | $25 / mo | hosted |
How to choose
- Calendar services coveredCheck which calendar services the API reads and writes, since an agent that must book across more than one service needs each one connected through the same integration.
- Time zones and availability logicTest a slot that crosses a daylight saving change in several time zones, since wrong offsets can book a meeting at the wrong hour for an attendee.
- Webhook notifications and retriesCheck how change notifications reach the agent and whether failed ones are retried, because an agent that misses a cancellation may keep treating a slot as taken.
- Cost for every accountWork out the bill for every account the agent will manage, since charges may apply to accounts that are only read.
How the benchmark tests this category. An agent finds a free slot across a Google and a Microsoft calendar, books it, moves it and cancels it. We check availability accuracy, time zones, webhook delivery and the cost per connected account.
Each one in detail
Google Calendar API
A 80.6/100Google Calendar's REST API for accessing calendars and managing events.
Verdict 21 OAuth scopes, including free/busy only and read-only on owned calendars. Google calendars only.
Choose it for An agent acting on Google Workspace or Gmail users' own calendars with tight scopes and no per-account fee.
Strengths
- 21 OAuth scopes, including free/busy only and read-only on owned calendars
- Every error reason documented with a recommended action, such as re-sync on 410
- Client-supplied event IDs (409 on a duplicate) and ETags (412 on a stale write) for safe retries
Weaknesses
- Google calendars only
- OAuth consent screen, Cloud project and app verification for sensitive or restricted scopes before real users can connect
- No booking pages, and slot finding only through the preview MCP's
suggest_time; the REST API returns raw free/busy
Price FreeAuth OAuthx402 nohosted
Nylas Calendar and Scheduler API
BB 71/100Unified calendar API over Google, Microsoft 365 and Outlook, Exchange (EWS) and iCloud.
Verdict 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.
Choose it for Products that need read, write and availability across every major provider plus email on one grant, from a handful of users upwards.
Strengths
- One schema across Google, Microsoft 365, Exchange EWS, iCloud and virtual calendars
- Free plan with 5 connected accounts and no card
- MCP docs warn about hidden instructions in calendar events and email, and sends need a confirmation call
Weaknesses
- API keys can't be scoped, so the MCP and any agent holding a key reach every grant
- No idempotency key on event writes, only on email send
- Several status incidents since July on email, IMAP and webhooks, including about six hours on 10 September
Price $15 / moAuth OAuth or keyx402 nohosted
Calendly API + MCP
B 68.3/100Calendly's scheduling API for availability, bookings, invitees and webhooks, with a hosted MCP server.
Verdict Per-resource OAuth scopes for new apps and personal access tokens, plus read and write scopes on the MCP. Booking through the API needs a paid seat, and Free users get a 403.
Choose it for Best when the host already schedules through Calendly and the agent needs to find a slot and book or cancel it.
Strengths
- Per-resource OAuth scopes for new apps and personal access tokens, plus read and write scopes on the MCP
- MCP tools annotated with readOnlyHint, destructiveHint and idempotentHint
- OpenAPI 3.1 in JSON and YAML, llms.txt and Markdown copies of every page
Weaknesses
- Booking through the API needs a paid seat, and Free users get a 403
- Booking limited to 10 a minute, 50 an hour and 100 a day per user below Enterprise
- No idempotency key on POST /invitees
Price $10 / seat-moAuth OAuth or keyx402 nohosted
Microsoft Graph Calendar API
B 65.1/100Calendar endpoints of Microsoft Graph for Outlook, Microsoft 365 and Exchange Online.
Verdict findMeetingTimes suggests slots across attendees and rooms, and getSchedule returns free/busy for many people. 4 concurrent requests per app per mailbox.
Choose it for Agents working inside Microsoft 365 tenants, especially when they need meeting-time suggestions across people and rooms.
Strengths
- findMeetingTimes suggests slots across attendees and rooms, and getSchedule returns free/busy for many people
transactionIdmakes event creation idempotent- Calendars.ReadBasic plus RBAC for Applications to limit an app to chosen mailboxes
Weaknesses
- 4 concurrent requests per app per mailbox
- Admin consent needed for application permissions across a tenant
- The npm JavaScript client is 3.0.7 from September 2023, without the June 2026 token-leak fix
Price Your planAuth OAuthx402 nohosted
Cronofy API
B 64.2/100Calendar sync and scheduling API from a UK company.
Verdict OAuth scopes as narrow as free_busy, with delete_event separate from create_event. Production pricing starts at $819 a month billed yearly.
Choose it for Products that schedule across many people and rooms with strict data residency, especially in the UK and EU.
Strengths
- OAuth scopes as narrow as
free_busy, withdelete_eventseparate fromcreate_event - Event writes keyed on your
event_id, so a retried create updates instead of duplicating - 99.99% uptime guarantee on Emerging and Growth
Weaknesses
- Production pricing starts at $819 a month billed yearly
- No OpenAPI spec or security.txt
- The changelog has no dates and its latest entries are years old
Price $819 / moAuth OAuth or keyx402 nohosted
Cal.com API v2 + MCP
C 57.2/100Scheduling API behind Cal.com's booking pages.
Verdict OAuth scopes split into READ and WRITE per resource, with 30-minute access tokens and PKCE. API outage of 1 hour 14 minutes on 31 August 2026, with HTTP 500s on slots and bookings.
Choose it for An agent that books, reschedules and cancels meetings into a Cal.com user's event types, or routes leads with routing forms.
Strengths
- OAuth scopes split into READ and WRITE per resource, with 30-minute access tokens and PKCE
- Hosted MCP with 63 tools and a
toolsetsparameter to load only the groups needed - OpenAPI 3.0 spec, llms.txt and Markdown reference pages
Weaknesses
- API outage of 1 hour 14 minutes on 31 August 2026, with HTTP 500s on slots and bookings
- 120 requests a minute by default and no documented 429 or retry behaviour
- Closed source since April 2026, and the npm MCP package hasn't changed since May 2025
Price $12 / seat-moAuth OAuth or keyx402 nohosted and local
Zoom Scheduler API
D 50.6/100Zoom's REST API for Zoom Scheduler, its appointment booking product. It reads schedules, availability and scheduled events, lists open slots, creates and cancels bookings and sends booking webhooks, with OAuth access on api.zoom.us.
Verdict Each of the 24 operations has its own granular OAuth scope, and Zoom Scheduler and the REST API are separate components on the status page. No operation moves a booking, no official SDK covers Scheduler, and Zoom's API terms forbid benchmarking or monitoring the service.
Choose it for An agent booking into a Zoom Scheduler user's or team's booking pages, with slot lookup, booking, cancellation and two webhooks.
Strengths
- Granular OAuth scopes per operation, with separate read, write, update and delete scopes and user and admin variants
- A slot lookup (
GET /scheduler/schedules/{scheduleId}/available_times) and a booking call (POST /scheduler/attendee), added in July and June 2026 - llms.txt and a Markdown copy of the full reference, with request examples and 400, 401, 404, 409, 429 and 500 responses listed
Weaknesses
- Zoom's API terms (section 3.7.9) forbid using the APIs to monitor availability or performance, or for benchmarking. This matters before any probe is run
- No operation moves a booking.
PATCH /scheduler/events/{eventId}changes status, notes and no-show marks only - No idempotency key or safe-retry guidance for booking writes was found in the reviewed documentation
Price $5.99 / seat-moAuth OAuthx402 nohosted
Aurinko Calendar API
E 45.6/100Unified calendar REST API from Yoxel, Inc. It reads and writes calendars and events on Google, Office 365, Outlook.com, Exchange and iCloud through one interface, with free/busy queries, booking profiles and webhooks.
Verdict A public OpenAPI 3.0 spec covers 154 operations, with free/busy, meeting-time suggestion and booking profiles alongside calendar reads and writes, and prices start at $1 an active account a month. No status page, SLA, changelog or official SDK was found, and the application's client secret reaches every connected account.
Choose it for A product that connects many users' Google and Microsoft calendars and wants availability and booking at a low price per account.
Strengths
- Public OpenAPI 3.0 spec at
apirefs.aurinko.io/assets/swagger.jsonwith 154 operations, 110 of them carrying a cURL sample - Availability in three forms,
/v1/calendars/freeBusy,/v1/calendars/suggestMeetingTimesand booking profiles for one calendar or a group - Prices published per active account a month ($1, $1.50 and $2), with a 14-day trial that needs no card
Weaknesses
- No status page, incident history or SLA found, and the terms supply the service as is
- No changelog, deprecation policy or official SDK. The only npm package,
aurinko-sdk, is unofficial - The application's client ID and secret, sent as Basic auth with
X-Aurinko-Account-Id, reach every connected account
Price PaidAuth OAuthx402 nohosted
Acuity Scheduling API
E 42.4/100Acuity Scheduling is Squarespace's appointment booking product. Its REST API reads availability, creates, reschedules and cancels appointments, manages clients and blocked time, and sends webhooks, with Basic authentication or OAuth2.
Verdict 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.
Choose it 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.
Strengths
- Availability by date and time, booking, rescheduling and cancelling are separate documented endpoints under
/api/v1 - Errors return a status code, a named
errorcode and a message, and a 404 suggests the nearest valid path - Webhooks are signed with HMAC-SHA256 in
x-acuity-signatureand retried nine times over 24 hours
Weaknesses
- The pricing page lists custom API access on Premium only, $61 a month or $49 billed yearly
- OAuth2 has one scope,
api-v1, and Basic authentication uses one account API key, so no read-only credential exists - No changelog or deprecation policy was found, and the Developer Terms allow changes without notice
Price $61 / moAuth OAuth or keyx402 nohosted
Apiroc Unified Calendar API
E 41.1/100Unified calendar API over Google Calendar, Microsoft Outlook (Office 365, Exchange and Outlook.com) and iCloud.
Verdict $0.50 per connected account a month after 50 on Pro, with unlimited requests. No status page history, changelog, OpenAPI spec, llms.txt or security.txt.
Choose it for A small product or an agent builder that needs read and write across Google, Microsoft and iCloud for tens to hundreds of accounts on a tight budget.
Strengths
- $0.50 per connected account a month after 50 on Pro, with unlimited requests
- Free plan for 10 accounts with no card
- Google, Outlook (Office 365, Exchange, Outlook.com) and iCloud behind one schema, with sync tokens for incremental reads
Weaknesses
- No status page history, changelog, OpenAPI spec, llms.txt or security.txt
- One application key reaches every connected account, with no key scopes documented
- No SLA on any plan, and no 429 or retry guidance in the docs
Price $25 / moAuth OAuth or keyx402 nohosted
Head to head
- Google Calendar API vs Nylas Calendar and Scheduler API A 80.6 vs BB 71
- Calendly API + MCP vs Google Calendar API B 68.3 vs A 80.6
- Google Calendar API vs Microsoft Graph Calendar API A 80.6 vs B 65.1
- Cronofy API vs Google Calendar API B 64.2 vs A 80.6
- Calendly API + MCP vs Nylas Calendar and Scheduler API B 68.3 vs BB 71
- Microsoft Graph Calendar API vs Nylas Calendar and Scheduler API B 65.1 vs BB 71
- Cronofy API vs Nylas Calendar and Scheduler API B 64.2 vs BB 71
- Calendly API + MCP vs Microsoft Graph Calendar API B 68.3 vs B 65.1
- Calendly API + MCP vs Cronofy API B 68.3 vs B 64.2
- Cronofy API vs Microsoft Graph Calendar API B 64.2 vs B 65.1
Questions
What are the highest-rated calendar and scheduling APIs for AI agents?
Google Calendar API has the highest benchmark score of the 10 ranked calendar and scheduling APIs, 80.6 (A). Nylas Calendar and Scheduler API is second with 71 (BB).
How many calendar and scheduling APIs are agent-ready?
2 of the 10 ranked here grade BB or better, the bar for agent-ready on the Anchor benchmark.
Which calendar and scheduling APIs accept x402 payments?
None of the ranked listings here accepts x402 for its main call yet.
How is this list ranked?
By the Anchor benchmark score out of 100, a weighted mean of the scored categories minus deductions for negative events, from public evidence re-checked as vendors change. Listings cannot pay for a place. The latest assessment behind this page is from 9 October 2026.
How this list is made
The order is the Anchor benchmark score, the same number as on each listing and in the top list. Each listing is graded from public evidence against the benchmark checklist, and the picks above are worked out from those grades, prices and facts. No listing pays for its place, and paid audits or listing help never change a score.
Full ranked table · 45 head-to-head comparisons · Best tools in every category