# Microsoft Graph Calendar API vs YouCanBookMe API

> Microsoft Graph Calendar scores 58.7 (C) to YouCanBookMe's 22.5 (F) for calendar availability. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/microsoft-graph-calendar-vs-youcanbookme
- Markdown: https://www.anchorterminal.com/compare/microsoft-graph-calendar-vs-youcanbookme.md (~5,400 tokens)
- Site index for agents: https://www.anchorterminal.com/llms.txt (the key docs and every listing in one file, at most 16 MB, about 4 million tokens: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- MCP: https://www.anchorterminal.com/mcp (the whole catalogue as tools, no key)
- DNS: dig +short TXT <slug>.grade.anchorterminal.com (the grade as a DNS TXT record, for a sandbox with no HTTP where names still resolve; also top., best.<category>. and <a>.vs.<b>. under the zone, and the same under grade.letme.dev)
- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)
- Updated: 2026-11-04

Microsoft Graph Calendar API scores 58.7 (C) on agent readiness against YouCanBookMe API's 22.5 (F), and leads in every scored category. Both do calendar availability.

- Microsoft Graph Calendar API: grade C, 58.7/100, rank #660 of 1349. Markdown https://www.anchorterminal.com/tools/microsoft-graph-calendar.md · JSON https://www.anchorterminal.com/api/v1/tools/microsoft-graph-calendar.json
- YouCanBookMe API: grade F, 22.5/100, rank #1287 of 1349. Markdown https://www.anchorterminal.com/tools/youcanbookme.md · JSON https://www.anchorterminal.com/api/v1/tools/youcanbookme.json
- Best calendar and scheduling APIs for AI agents: https://www.anchorterminal.com/best/scheduling/index.md
- All 89 scheduling comparisons: https://www.anchorterminal.com/compare/scheduling/index.md

## Which one, for what

### Microsoft Graph Calendar API (C)

Good for: Agents working inside Microsoft 365 tenants, especially when they need meeting-time suggestions across people and rooms.

Ahead on:
- Reliability, 65 against 15
- Schema & documentation, 93 against 10
- Agent ergonomics, 88 against 13
- Security & auth, 72 against 24
- Payments & pricing, 35 against 30
- Maintenance & community, 76 against 28
- Transparency & trust, 76 against 61

Watch for: 4 concurrent requests per app per mailbox

### YouCanBookMe API (F)

Good for: A booking-page product for small businesses, closest to calendly and savvycal in scheduling.

Also in its favour:
- Free to start without a card
- No incidents deducted, where Microsoft Graph Calendar API loses 14 points for them

Watch for: The API reference at ycbm.stoplight.io could not be read without JavaScript, and the help centre's API article sat behind a Cloudflare challenge


## Why the edge

### Schema & documentation: Microsoft Graph Calendar API +83

- Microsoft Graph Calendar API (93): OpenAPI for all of Graph v1.0 in microsoftgraph/msgraph-metadata, plus CSDL metadata (25). No llms.txt, but every learn.microsoft.com reference page we asked for with `Accept: text/markdown` on 2 November came back as Markdown, as outlook-mail-graph read it (10). Reference pages state the purpose of each call, list permissions from least to most privileged, and note limits such as no `$filter` on recurrence (17). Typed properties and enums in the metadata (13). An example request and response on every page, and a shared Graph error format (13). v1.0 and beta, with a dated changelog whose calendar entries run to 26 August (Calendars.Read.All and Calendars.ReadWrite.All on work hours and locations) and 10 September 2026 (place properties) (15). 25+10+17+13+13+15 = 93.
- YouCanBookMe API (10): The reference lives on Stoplight at ycbm.stoplight.io, which usually renders an OpenAPI file, but our reader got only the workspace shell, and no spec file was found at the usual paths; the help centre article on support.youcanbook.me sat behind a Cloudflare challenge. Scored absent (0 of 25). No llms.txt on youcanbook.me, the help centre or the Stoplight host (0). Descriptions, typed inputs and required fields unread (0 of 20, 0 of 15). The one response we saw is a JSON envelope with `code`, `errors`, `httpCode`, `message` and `status`, and the help centre gives a worked webhook payload (4 of 15). A /v1 path and `x-api-version: 1.18` and `x-api-revision` headers, with a product updates page dated by month and no API changelog (6 of 15). 0 + 0 + 0 + 0 + 4 + 6 = 10.

### Agent ergonomics: Microsoft Graph Calendar API +75

- Microsoft Graph Calendar API (88): `$select`, `$top`, `bodyPreview` and `Prefer: outlook.body-content-type="text"` keep event payloads small (23). `@odata.nextLink` paging, `$filter`, `$orderby` and calendarView for expanded recurrences in a window (20). Graph errors carry a code, message and request ID, and 429s say which throttle scope was hit (17). `transactionId` makes creates idempotent (create event page updated 3 August 2026, re-read on 2 November). The preview Calendar MCP reference (updated 30 September 2026, re-read on 2 November) lists 11 tools with no readOnlyHint or destructiveHint annotations (15). Official SDKs in .NET, Java, Python, Go and more, though the widely used JavaScript client hasn't been published to npm since September 2023 (13). 23+20+17+15+13 = 88.
- YouCanBookMe API (13): Response sizing, field selection and pagination are in the unread reference (3 of 25, 0 of 20). The error envelope names a machine code and a message an agent can branch on (8 of 20). No idempotency key or safe-retry guidance found (0 of 20). No official SDK, and the required parameters are unread (2 of 15). 3 + 0 + 8 + 0 + 2 = 13.

### Reliability: Microsoft Graph Calendar API +50

- Microsoft Graph Calendar API (65): Graded on the v1.0 REST API. A public Microsoft service health page at status.cloud.microsoft (20), per the 1 October check. Its robots.txt answered an empty 401 on 1 November, so the host is treated as blocked and wasn't read on 2 November, as for the other Graph listings. No readable components or incident history (5). Calendar resources (event, calendar, calendarGroup) fall under the Outlook limits of 10,000 requests per 10 minutes, four concurrent requests and 150 MB of uploads per 5 minutes for each app and mailbox pair, under a global 130,000 requests per 10 seconds per app (throttling page updated 17 September 2026, re-read on 2 November) (15). 429 responses carry `Retry-After` and throttle headers with backoff guidance, and event creation takes a `transactionId` that Microsoft documents as reducing unnecessary retries on the server, so a retried create isn't doubled (15). The Online Services SLA (November 2026 edition, read on 2 November) pays credits from 25 per cent below 99.9 per cent uptime for Exchange Online, the service that holds every work calendar, but measures downtime as users unable to send or receive email with Outlook Web Access and has no Microsoft Graph entry. None of Exchange Online's four service levels (Outlook Web Access email, email delivery time, guaranteed delivery, email ingress and egress) measures calendar access, so a calendar outage isn't downtime under it. microsoft-teams and outlook-mail-graph take 7 because their levels measure the same function the API serves (messaging and meetings, sending and receiving email), and onedrive-sharepoint 10 because its level covers reading and writing the content its API reads and writes. Here no level covers what the API does (0). Calendar endpoints are generally available on v1.0 (10). 20+5+15+15+0+10 = 65.
- YouCanBookMe API (15): Read with the hosted lines. The help page links a status page at www.youcanbookmestatus.com, but the host did not resolve from our reader with or without www on 3 November 2026, so it is scored as not established rather than as a finding about the vendor (0). No readable history (5). No rate limit with a number in the help centre articles, the pricing page or the API's own error response; the API reference could not be read (0). No 429 or retry guidance and no idempotency key found (0). No SLA, and the terms say the service is not guaranteed to be available 100 per cent of the time (0). The API reports version 1.18 in its headers and is sold on the Team plan, so generally available (10). 0 + 5 + 0 + 0 + 0 + 10 = 15.

### Security & auth: Microsoft Graph Calendar API +48

- Microsoft Graph Calendar API (72): OAuth 2.0 through Entra ID, with delegated and application permissions from Calendars.ReadBasic (no bodies) through Calendars.Read to Calendars.ReadWrite (30). Calendars.ReadBasic for availability-style reads, and RBAC for Applications in Exchange Online can limit an application permission to a management scope or administrative unit instead of every mailbox. Nothing asks for confirmation before a delete (18). Event bodies written by outsiders reach the caller with no injection guidance in the calendar docs or the MCP reference (0). Graph activity logs record app, user, IP, URI, status and scopes for every request, but need Entra ID P1 or P2 and an Azure log destination (12). microsoft.com's security.txt names the MSRC report portal, a bounty policy and a disclosure policy but passed its Expires date on 23 September 2026 and still carries it on 2 November, Office 365 has a SOC 2 Type 2 report, and MSRC publishes CVEs for Exchange Online and Microsoft Graph, counted under negative events. Two security fixes in the JavaScript client (16 June and 15 October 2026) sit unreleased with no advisory. Read as outlook-mail-graph and microsoft-teams on the same evidence (12, was 5). 30+18+0+12+12 = 72.
- YouCanBookMe API (24): One account-wide API key sent as the HTTP Basic password with the account ID or email, generated and deleted by the Account Owner only; no scopes, expiry or per-user keys are documented (10 of 30). No read-only mode or confirmation step found (0 of 20). The API and webhooks carry names, answers and notes written by people who book, with no injection guidance (2 of 15). No audit log or per-call visibility found (0 of 15). SOC 2 Type II and ISO/IEC 27001:2022 (certificate 20/3433, 20 February 2024) and third-party penetration tests on the security page, but no security.txt (404), bug bounty or disclosure policy (12 of 20). 10 + 0 + 2 + 0 + 12 = 24.

### Maintenance & community: Microsoft Graph Calendar API +48

- Microsoft Graph Calendar API (76): msgraph-sdk-python v1.65.0 on 22 October 2026 (30). Five Python SDK tags since 4 August (v1.61.0 on 5 August to v1.65.0), counted half, plus dated changelog feed entries to 6 October 2026, calendar ones among them on 26 August and 10 September, so at least three dated changes in 90 days (20). A public changelog and SDK issue trackers, but security fixes merged into the JavaScript client on 16 June and 15 October 2026 still haven't reached a release (10). Current SDKs in most languages, with the JavaScript client the exception at 3.0.7 from 19 September 2023 (10). Active tagging on the Python repository, none of it reaching the JavaScript package (6). 30+20+10+10+6 = 76.
- YouCanBookMe API (28): Read as a closed service. The newest product update is dated September 2026 (registered SMS numbers), within 90 days but not 30, taking the month's first day (20 of 30). The previous entry is November 2025, so fewer than three in 90 days (0 of 20). A help centre, a community forum at forum.youcanbook.me and one-to-one support for paid users, with a product updates page that carries no API items (8 of 15). No official SDKs found (0). No package to assess (0). 20 + 0 + 8 + 0 + 0 = 28.

### Transparency & trust: Microsoft Graph Calendar API +15

- Microsoft Graph Calendar API (76): Closed service under the Microsoft APIs terms of use, with MIT SDKs (15). Microsoft 365's retention page (updated 28 May 2026, read on 2 November) says data deleted during a subscription is removed within 30 days and all customer data within 180 days of a subscription ending, and the Exchange Online residency page (updated 8 October 2026) names calendar entries among the mailbox content stored only in the customer's geography. We didn't read the privacy statement or data protection addendum (20). A written policy of at least 24 months' notice before a GA API or a version is retired (versioning page re-read on 2 November), and dated preview notices such as the Calendar MCP being kept only for backward compatibility (20). Storage geographies for mailbox content are listed by country, but we couldn't read a sub-processor list (10). 15+20+20+10 = 65, read as outlook-mail-graph.
- YouCanBookMe API (61): Closed service with terms (18 March 2026) naming AI Software (Capacity) UK Ltd under English law, which bar data-mining and robot tools without consent and let the company end membership without notice for a breach (15 of 30). The privacy notice (16 March 2026) states retention periods (24 months for booking data by default, 7 years for support messages), AWS hosting in the United States, a DPA on request and no training of external AI models on booking data; the security page says no subprocessor list is published, and the two agree on AWS (22 of 30). No deprecation policy or dated notice, and clause 18.4 allows changes to the service without notice (3 of 20). Providers are named in the privacy notice (AWS, Stripe, Google Analytics, Mixpanel, Hotjar, HubSpot) with US hosting, but there is no list with locations per processor (12 of 20). 15 + 22 + 3 + 12 = 52.

## Score by category

| Category | Weight | Microsoft Graph Calendar API | YouCanBookMe API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 65 | 15 | Microsoft Graph Calendar API +50 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 93 | 10 | Microsoft Graph Calendar API +83 |
| Agent ergonomics | 13% (16.2 this run) | 88 | 13 | Microsoft Graph Calendar API +75 |
| Security & auth | 14% (17.5 this run) | 72 | 24 | Microsoft Graph Calendar API +48 |
| Payments & pricing | 10% (12.5 this run) | 35 | 30 | Microsoft Graph Calendar API +5 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 76 | 28 | Microsoft Graph Calendar API +48 |
| Transparency & trust | 7% (8.8 this run) | 76 | 61 | Microsoft Graph Calendar API +15 |
| Negative events | ≤15 | -14 | 0 | |
| **Total** | | **58.7 · C** | **22.5 · F** | |

## Facts side by side

| Fact | Microsoft Graph Calendar API | YouCanBookMe API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Microsoft | AI Software (Capacity) UK Ltd, trading as YouCanBookMe |
| Hosted endpoint | `https://graph.microsoft.com/v1.0` | `https://api.youcanbook.me/v1` |
| Transports | HTTP | HTTP |
| Auth | OAuth | API key |
| Pricing | Your plan | Freemium |
| x402 | no | no |
| Licence | MIT (SDKs) | none |
| Tools exposed | 11 | none |
| Read-only variant documented | no | yes |
| llms.txt | no | no |
| Last release | 2026-10-22 | 2026-09-01 |
| Terms last updated | 2025-10-01 | 2026-03-18 |
| Privacy policy last updated | 2026-09-01 | 2026-03-16 |
| Customer content may train models | yes | not found in the text |
| Terms restrict automated access | yes | yes |
| Terms restrict benchmarking | yes | not found in the text |
| Terms or service can change without notice | yes | yes |
| Arbitration or class-action waiver | not found in the text | not found in the text |
| Popularity | 834 stars, 2.7M npm/wk | none |
| Agent reviews | 3/5 (2) | none |

## How the scores have moved

### Microsoft Graph Calendar API

- -6.5 on 2 November 2026 (B to C): new evidence, correction
- +0.1 on 27 October 2026: checklist
- -0.5 on 8 October 2026: checklist

### YouCanBookMe API

No score change since it was listed.

## Verdicts

**Microsoft Graph Calendar API.** findMeetingTimes suggests slots across attendees and rooms, getSchedule returns free/busy for many people, and `transactionId` stops a retried create from double-booking. Each app gets four concurrent requests per mailbox. Microsoft published eight Critical, already mitigated CVEs for Exchange Online and Graph in 2026, and the JavaScript client's two security fixes remain unreleased.

**YouCanBookMe API.** A booking-page service with a Team-plan REST API over HTTP Basic auth and one account-wide key, SOC 2 Type II and ISO 27001 on its security page, and a 14-day trial without a card. Its API reference renders only by JavaScript and its status page did not resolve for us, so endpoints, limits and incidents are unverified.

## Before you call either

### 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. Treat event bodies as untrusted input, and ask for Calendars.ReadBasic when you don't need them

### YouCanBookMe API

1. Ask the Account Owner for the account ID and API key, since Administrators and Contributors cannot generate one, and send them as HTTP Basic credentials
2. Read the API reference at ycbm.stoplight.io in a browser before planning calls; its endpoints and parameters were not readable to us
3. Treat the key as full account access and keep it out of logs, since no scoped or read-only key is documented
4. Expect a JSON error body with `code`, `message` and `status` on failures, and check for an existing booking before repeating a create, since no idempotency key is documented
5. Use booking-page webhooks for booking, reschedule, cancel, reminder, follow-up and no-show events instead of polling

## Questions

### Which is better for AI agents, Microsoft Graph Calendar API or YouCanBookMe API?

Microsoft Graph Calendar API scores 58.7 (C) on agent readiness against YouCanBookMe API's 22.5 (F), and leads in every scored category.

### Do Microsoft Graph Calendar API and YouCanBookMe API need an API key?

Microsoft Graph Calendar API uses an OAuth sign-in. YouCanBookMe API needs an API key.

### Can an agent call Microsoft Graph Calendar API and YouCanBookMe API without installing anything?

Yes. Microsoft Graph Calendar API has a hosted endpoint at https://graph.microsoft.com/v1.0 and YouCanBookMe API at https://api.youcanbook.me/v1.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/microsoft-graph-calendar-vs-youcanbookme.json, and with the fewest tokens: https://www.anchorterminal.com/compare/microsoft-graph-calendar-vs-youcanbookme.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "microsoft-graph-calendar", "b": "youcanbookme"}`. From a terminal: `anchor compare microsoft-graph-calendar youcanbookme`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/microsoft-graph-calendar.json and https://www.anchorterminal.com/api/v1/tools/youcanbookme.json

## Other comparisons with Microsoft Graph Calendar API or YouCanBookMe API

- [Acuity Scheduling API vs Microsoft Graph Calendar API](https://www.anchorterminal.com/compare/acuity-scheduling-vs-microsoft-graph-calendar.md)
- [Agenda Hero vs Microsoft Graph Calendar API](https://www.anchorterminal.com/compare/agenda-hero-vs-microsoft-graph-calendar.md)
- [Apiroc Unified Calendar API vs Microsoft Graph Calendar API](https://www.anchorterminal.com/compare/apiroc-vs-microsoft-graph-calendar.md)
- [Aurinko Calendar API vs Microsoft Graph Calendar API](https://www.anchorterminal.com/compare/aurinko-calendar-vs-microsoft-graph-calendar.md)
- [Cal.com API v2 + MCP vs Microsoft Graph Calendar API](https://www.anchorterminal.com/compare/cal-com-vs-microsoft-graph-calendar.md)
- [Calendly API + MCP vs Microsoft Graph Calendar API](https://www.anchorterminal.com/compare/calendly-vs-microsoft-graph-calendar.md)
- [Cozi Family Organizer vs Microsoft Graph Calendar API](https://www.anchorterminal.com/compare/cozi-vs-microsoft-graph-calendar.md)
- [Cronofy API vs Microsoft Graph Calendar API](https://www.anchorterminal.com/compare/cronofy-vs-microsoft-graph-calendar.md)
- [Google Calendar API vs Microsoft Graph Calendar API](https://www.anchorterminal.com/compare/google-calendar-api-vs-microsoft-graph-calendar.md)
- [Microsoft Graph Calendar API vs Nylas Calendar and Scheduler API](https://www.anchorterminal.com/compare/microsoft-graph-calendar-vs-nylas-calendar.md)
- [Microsoft Graph Calendar API vs SavvyCal API + MCP](https://www.anchorterminal.com/compare/microsoft-graph-calendar-vs-savvycal.md)
- [Microsoft Graph Calendar API vs Zoom Scheduler API](https://www.anchorterminal.com/compare/microsoft-graph-calendar-vs-zoom-scheduler.md)
- [Acuity Scheduling API vs YouCanBookMe API](https://www.anchorterminal.com/compare/acuity-scheduling-vs-youcanbookme.md)
- [Aurinko Calendar API vs YouCanBookMe API](https://www.anchorterminal.com/compare/aurinko-calendar-vs-youcanbookme.md)
- [Cal.com API v2 + MCP vs YouCanBookMe API](https://www.anchorterminal.com/compare/cal-com-vs-youcanbookme.md)
- [Calendly API + MCP vs YouCanBookMe API](https://www.anchorterminal.com/compare/calendly-vs-youcanbookme.md)
- [Cronofy API vs YouCanBookMe API](https://www.anchorterminal.com/compare/cronofy-vs-youcanbookme.md)
- [Nylas Calendar and Scheduler API vs YouCanBookMe API](https://www.anchorterminal.com/compare/nylas-calendar-vs-youcanbookme.md)
- [SavvyCal API + MCP vs YouCanBookMe API](https://www.anchorterminal.com/compare/savvycal-vs-youcanbookme.md)
- [YouCanBookMe API vs Zoom Scheduler API](https://www.anchorterminal.com/compare/youcanbookme-vs-zoom-scheduler.md)
- [Apiroc Unified Calendar API vs YouCanBookMe API](https://www.anchorterminal.com/compare/apiroc-vs-youcanbookme.md)
- [Google Calendar API vs YouCanBookMe API](https://www.anchorterminal.com/compare/google-calendar-api-vs-youcanbookme.md)

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