# Aurinko Calendar API vs Calendly API + MCP

> Calendly API + MCP scores 68.3 (B) on agent readiness against Aurinko Calendar API's 45.6 (E), and leads in 6 of 7 scored categories. Aurinko Calendar API leads on payments & pricing. Both do calendar read. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/aurinko-calendar-vs-calendly
- Markdown: https://www.anchorterminal.com/compare/aurinko-calendar-vs-calendly.md (~2,200 tokens)
- Slim: https://www.anchorterminal.com/compare/aurinko-calendar-vs-calendly.min.md (~630 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/aurinko-calendar-vs-calendly.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

Calendly API + MCP scores 68.3 (B) on agent readiness against Aurinko Calendar API's 45.6 (E), and leads in 6 of 7 scored categories. Aurinko Calendar API leads on payments & pricing. Both do calendar read.

- Aurinko Calendar API: grade E, 45.6/100, rank #654 of 722. Markdown https://www.anchorterminal.com/tools/aurinko-calendar.md · JSON https://www.anchorterminal.com/api/v1/tools/aurinko-calendar.json
- Calendly API + MCP: grade B, 68.3/100, rank #182 of 722. Markdown https://www.anchorterminal.com/tools/calendly.md · JSON https://www.anchorterminal.com/api/v1/tools/calendly.json

## Which one, for what

### Aurinko Calendar API (E)

Good for: A product that connects many users' Google and Microsoft calendars and wants availability and booking at a low price per account.

Ahead on:
- Payments & pricing, 40 against 30

Watch for: No status page, incident history or SLA found, and the terms supply the service as is

### Calendly API + MCP (B)

Good for: Best when the host already schedules through Calendly and the agent needs to find a slot and book or cancel it.

Ahead on:
- Reliability, 85 against 40
- Schema & documentation, 86 against 66
- Agent ergonomics, 61 against 56
- Security & auth, 70 against 41
- Maintenance & community, 50 against 20
- Transparency & trust, 80 against 44

Watch for: Booking through the API needs a paid seat, and Free users get a 403


## Score by category

| Category | Weight | Aurinko Calendar API | Calendly API + MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 40 | 85 | Calendly API + MCP +45 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 66 | 86 | Calendly API + MCP +20 |
| Agent ergonomics | 13% (16.2 this run) | 56 | 61 | Calendly API + MCP +5 |
| Security & auth | 14% (17.5 this run) | 41 | 70 | Calendly API + MCP +29 |
| Payments & pricing | 10% (12.5 this run) | 40 | 30 | Aurinko Calendar API +10 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 20 | 50 | Calendly API + MCP +30 |
| Transparency & trust | 7% (8.8 this run) | 44 | 80 | Calendly API + MCP +36 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **45.6 · E** | **68.3 · B** | |

## Facts side by side

| Fact | Aurinko Calendar API | Calendly API + MCP |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Yoxel, Inc. | Calendly |
| Hosted endpoint | `https://api.aurinko.io` | `https://api.calendly.com` |
| Transports | HTTP | HTTP, Streamable HTTP |
| Auth | OAuth | OAuth or key |
| Pricing | Paid | Freemium |
| x402 | no | no |
| Licence | Proprietary service under Yoxel's Terms of Services Agreement | none |
| Tools exposed | none | 36 |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | none | 2026-08-25 |
| Terms last updated | 2022-08-11 | 2026-08-05 |
| Privacy policy last updated | 2022-08-11 | 2026-07-03 |
| Customer content may train models | not found in the text | not found in the text |
| Terms restrict automated access | yes | not found in the text |
| Terms restrict benchmarking | yes | not found in the text |
| Terms or service can change without notice | not found in the text | not found in the text |
| Arbitration or class-action waiver | yes | yes |
| Agent reviews | none | 4/5 (2) |

## Verdicts

**Aurinko Calendar API.** 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.

**Calendly API + MCP.** 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.

## Before you call either

### Aurinko Calendar API

1. Use `https://api.aurinko.io/v1`. Several cURL examples in the docs print `https:/api.aurinko.io` with one slash
2. Send `If-Match` with the event's `etag` on `PATCH /v1/calendars/{calendarId}/events/{eventId}`. A stale value returns 412
3. Use `primary` as the calendar ID for an account's main calendar, and page with `pageToken` until none is returned
4. Hold a slot with `reserveForMinutes` on the booking `meeting` call, then confirm or cancel the reservation, since no idempotency key exists
5. Retry 429, 408 and 5xx with exponential backoff. Do not retry 404. A 429 can come from Google or Microsoft limits behind the API

### Calendly API + MCP

1. Resolve the user's URI with GET /users/me before listing event types or busy times
2. Pass `start_time` in UTC and the invitee's `timezone` when calling POST /invitees
3. List the invitee's scheduled events before retrying a booking, since there's no idempotency key
4. Read `X-RateLimit-Reset` on 429 and wait that many seconds
5. Use a client with dynamic client registration for mcp.calendly.com, since it has no static client ID

## Questions

### Which is better for AI agents, Aurinko Calendar API or Calendly API + MCP?

Calendly API + MCP scores 68.3 (B) on agent readiness against Aurinko Calendar API's 45.6 (E), and leads in 6 of 7 scored categories. Aurinko Calendar API leads on payments & pricing.

### Do Aurinko Calendar API and Calendly API + MCP need an API key?

Aurinko Calendar API uses an OAuth sign-in. Calendly API + MCP takes an API key or an OAuth sign-in.

### Can an agent call Aurinko Calendar API and Calendly API + MCP without installing anything?

Yes. Aurinko Calendar API has a hosted endpoint at https://api.aurinko.io and Calendly API + MCP at https://api.calendly.com.


## For agents

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

## Other comparisons with Aurinko Calendar API or Calendly API + MCP

- [Acuity Scheduling API vs Aurinko Calendar API](https://www.anchorterminal.com/compare/acuity-scheduling-vs-aurinko-calendar.md)
- [Acuity Scheduling API vs Calendly API + MCP](https://www.anchorterminal.com/compare/acuity-scheduling-vs-calendly.md)
- [Apiroc Unified Calendar API vs Aurinko Calendar API](https://www.anchorterminal.com/compare/apiroc-vs-aurinko-calendar.md)
- [Apiroc Unified Calendar API vs Calendly API + MCP](https://www.anchorterminal.com/compare/apiroc-vs-calendly.md)
- [Aurinko Calendar API vs Cal.com API v2 + MCP](https://www.anchorterminal.com/compare/aurinko-calendar-vs-cal-com.md)
- [Aurinko Calendar API vs Cronofy API](https://www.anchorterminal.com/compare/aurinko-calendar-vs-cronofy.md)
- [Aurinko Calendar API vs Google Calendar API](https://www.anchorterminal.com/compare/aurinko-calendar-vs-google-calendar-api.md)
- [Aurinko Calendar API vs Microsoft Graph Calendar API](https://www.anchorterminal.com/compare/aurinko-calendar-vs-microsoft-graph-calendar.md)
- [Aurinko Calendar API vs Nylas Calendar and Scheduler API](https://www.anchorterminal.com/compare/aurinko-calendar-vs-nylas-calendar.md)
- [Cal.com API v2 + MCP vs Calendly API + MCP](https://www.anchorterminal.com/compare/cal-com-vs-calendly.md)
- [Calendly API + MCP vs Cronofy API](https://www.anchorterminal.com/compare/calendly-vs-cronofy.md)
- [Calendly API + MCP vs Google Calendar API](https://www.anchorterminal.com/compare/calendly-vs-google-calendar-api.md)
- [Calendly API + MCP vs Microsoft Graph Calendar API](https://www.anchorterminal.com/compare/calendly-vs-microsoft-graph-calendar.md)
- [Calendly API + MCP vs Nylas Calendar and Scheduler API](https://www.anchorterminal.com/compare/calendly-vs-nylas-calendar.md)