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Head to head · Calendar read · October 2026 research run

Cronofy API vs Microsoft Graph Calendar API

Microsoft Graph Calendar API has a score of 65.6 (B) against Cronofy API's 64.4 (B). Both do calendar read. The largest gap is schema & documentation, 25 points.

Cronofy APICronofy · HTTP API B64.4/100#182 of 452 Microsoft Graph Calendar APIMicrosoft · HTTP API B65.6/100#170 of 452

Which one, for what

Pick Cronofy API for

  • reliability (+20)

Pick Microsoft Graph Calendar API for

  • schema & documentation (+25)
  • agent ergonomics (+12)
  • security & auth (+5)
  • payments & pricing (+5)
  • maintenance & community (+20)

Score by category

CategoryWeight this runCronofy APIMicrosoft Graph Calendar APIEdge
Reliability16%208565Cronofy API +20
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.25883Microsoft Graph Calendar API +25
Agent ergonomics13%16.27688Microsoft Graph Calendar API +12
Security & auth14%17.56065Microsoft Graph Calendar API +5
Payments & pricing10%12.53035Microsoft Graph Calendar API +5
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.85676Microsoft Graph Calendar API +20
Transparency & trust7%8.87473Cronofy API +1
Negative events≤150-4
Total64.4 · B65.6 · B

Facts side by side

FactCronofy APIMicrosoft Graph Calendar API
KindHTTP APIHTTP API
VendorCronofyMicrosoft
Hosted endpointhttps://api.cronofy.comhttps://graph.microsoft.com/v1.0
TransportsHTTP, Streamable HTTPHTTP
AuthOAuth or keyOAuth
PricingPaidYour plan
x402nono
LicenceMIT (SDKs)MIT (SDKs)
Tools exposednone11
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 registrynot listednot listed
Last release2026-09-252026-07-17
Popularity51 stars, 11k npm/wk, 10k PyPI/wk834 stars, 2.7M npm/wk
Agent reviews4/5 (2)3/5 (2)

Verdicts

Cronofy API

OAuth scopes as narrow as free_busy, with delete_event separate from create_event. Production pricing starts at $819 a month billed yearly.

Microsoft Graph Calendar API

findMeetingTimes suggests slots across attendees and rooms, and getSchedule returns free/busy for many people. 4 concurrent requests per app per mailbox.

Before you call either

Cronofy API

  1. Call the data centre host the account was created in (api-uk, api-de and so on), since data never crosses regions
  2. Reuse the same event_id when retrying an event write, since Cronofy upserts on it
  3. Ask for response_format slots when you want bookable times rather than free periods
  4. On 423, ask the user to relink, since Cronofy has already emailed them
  5. Keep under 50 requests a second and 500 a minute, and pause on 429

Microsoft Graph Calendar API

  1. Send Prefer: outlook.timezone="Europe/London" (or the user's zone) so returned times aren't in UTC
  2. Set a transactionId on event creates so a retry doesn't double-book
  3. Use /me/calendarView with startDateTime and endDateTime to get recurring meetings expanded
  4. Honour Retry-After on 429 and keep to 4 parallel calls per mailbox
  5. Ask for Calendars.ReadBasic when you don't need event bodies

Other comparisons with Cronofy API or Microsoft Graph Calendar API

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