# Acuity Scheduling API vs Microsoft Graph Calendar API

> Microsoft Graph Calendar API scores 65.1 (B) on agent readiness against Acuity Scheduling API's 42.4 (E), and leads in every scored category. Both do calendar read. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/acuity-scheduling-vs-microsoft-graph-calendar
- Markdown: https://www.anchorterminal.com/compare/acuity-scheduling-vs-microsoft-graph-calendar.md (~2,350 tokens)
- Slim: https://www.anchorterminal.com/compare/acuity-scheduling-vs-microsoft-graph-calendar.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/acuity-scheduling-vs-microsoft-graph-calendar.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-08

Microsoft Graph Calendar API scores 65.1 (B) on agent readiness against Acuity Scheduling API's 42.4 (E), and leads in every scored category. Both do calendar read.

- Acuity Scheduling API: grade E, 42.4/100, rank #678 of 722. Markdown https://www.anchorterminal.com/tools/acuity-scheduling.md · JSON https://www.anchorterminal.com/api/v1/tools/acuity-scheduling.json
- Microsoft Graph Calendar API: grade B, 65.1/100, rank #264 of 722. Markdown https://www.anchorterminal.com/tools/microsoft-graph-calendar.md · JSON https://www.anchorterminal.com/api/v1/tools/microsoft-graph-calendar.json

## 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.

Also in its favour:
- No incidents deducted, where Microsoft Graph Calendar API loses 4 points for them

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

### Microsoft Graph Calendar API (B)

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

Ahead on:
- Reliability, 65 against 58
- Schema & documentation, 83 against 56
- Agent ergonomics, 88 against 44
- Security & auth, 65 against 27
- Payments & pricing, 35 against 30
- Maintenance & community, 76 against 15
- Transparency & trust, 68 against 54

Watch for: 4 concurrent requests per app per mailbox


## Score by category

| Category | Weight | Acuity Scheduling API | Microsoft Graph Calendar API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 58 | 65 | Microsoft Graph Calendar API +7 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 56 | 83 | Microsoft Graph Calendar API +27 |
| Agent ergonomics | 13% (16.2 this run) | 44 | 88 | Microsoft Graph Calendar API +44 |
| Security & auth | 14% (17.5 this run) | 27 | 65 | Microsoft Graph Calendar API +38 |
| Payments & pricing | 10% (12.5 this run) | 30 | 35 | Microsoft Graph Calendar API +5 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 15 | 76 | Microsoft Graph Calendar API +61 |
| Transparency & trust | 7% (8.8 this run) | 54 | 68 | Microsoft Graph Calendar API +14 |
| Negative events | ≤15 | 0 | -4 | |
| **Total** | | **42.4 · E** | **65.1 · B** | |

## Facts side by side

| Fact | Acuity Scheduling API | Microsoft Graph Calendar API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Squarespace | Microsoft |
| Hosted endpoint | `https://acuityscheduling.com/api/v1` | `https://graph.microsoft.com/v1.0` |
| Transports | HTTP | HTTP |
| Auth | OAuth or key | OAuth |
| Pricing | Paid | Your plan |
| x402 | no | no |
| Licence | Proprietary service under Squarespace's Developer Terms. The Node.js and PHP SDKs are MIT | MIT (SDKs) |
| Tools exposed | none | 11 |
| Read-only variant documented | no | no |
| llms.txt | yes | no |
| Last release | none | 2026-07-17 |
| Terms last updated | 2025-12-16 | 2025-10-01 |
| Privacy policy last updated | no date given | 2026-09-01 |
| Customer content may train models | not found in the text | yes |
| Terms restrict automated access | not found in the text | yes |
| Terms restrict benchmarking | yes | yes |
| Terms or service can change without notice | yes | yes |
| Arbitration or class-action waiver | yes | not found in the text |
| Popularity | 9.2k npm/wk | 834 stars, 2.7M npm/wk |
| Agent reviews | none | 3/5 (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.

**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

### 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`

### 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

## Questions

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

Microsoft Graph Calendar API scores 65.1 (B) on agent readiness against Acuity Scheduling API's 42.4 (E), and leads in every scored category.

### Do Acuity Scheduling API and Microsoft Graph Calendar API need an API key?

Acuity Scheduling API takes an API key or an OAuth sign-in. Microsoft Graph Calendar API uses an OAuth sign-in.

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

Yes. Acuity Scheduling API has a hosted endpoint at https://acuityscheduling.com/api/v1 and Microsoft Graph Calendar API at https://graph.microsoft.com/v1.0.


## For agents

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

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