# Cal.com API v2 + MCP vs Cronofy API

> Cronofy API has a score of 64.4 (B) against Cal.com API v2 + MCP's 57.5 (C). Both do calendar read. The largest gap is agent ergonomics, 26 points. Category scores, facts, verdicts and agent notes side by side.

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- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-05

Cronofy API has a score of 64.4 (B) against Cal.com API v2 + MCP's 57.5 (C). Both do calendar read. The largest gap is agent ergonomics, 26 points.

- Cal.com API v2 + MCP: grade C, 57.5/100, rank #292 of 452. Markdown https://www.anchorterminal.com/tools/cal-com.md · JSON https://www.anchorterminal.com/api/v1/tools/cal-com.json
- Cronofy API: grade B, 64.4/100, rank #182 of 452. Markdown https://www.anchorterminal.com/tools/cronofy.md · JSON https://www.anchorterminal.com/api/v1/tools/cronofy.json

## Which one, for what

Pick Cal.com API v2 + MCP for schema & documentation (+18), transparency & trust (+7).

Pick Cronofy API for reliability (+25), agent ergonomics (+26), maintenance & community (+6).

## Score by category

| Category | Weight | Cal.com API v2 + MCP | Cronofy API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 60 | 85 | Cronofy API +25 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 76 | 58 | Cal.com API v2 + MCP +18 |
| Agent ergonomics | 13% (16.2 this run) | 50 | 76 | Cronofy API +26 |
| Security & auth | 14% (17.5 this run) | 56 | 60 | Cronofy API +4 |
| Payments & pricing | 10% (12.5 this run) | 30 | 30 | even |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 50 | 56 | Cronofy API +6 |
| Transparency & trust | 7% (8.8 this run) | 81 | 74 | Cal.com API v2 + MCP +7 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **57.5 · C** | **64.4 · B** | |

## Facts side by side

| Fact | Cal.com API v2 + MCP | Cronofy API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Cal.com | Cronofy |
| Hosted endpoint | `https://api.cal.com/v2` | `https://api.cronofy.com` |
| Transports | HTTP, Streamable HTTP, stdio | HTTP, Streamable HTTP |
| Auth | OAuth or key | OAuth or key |
| Pricing | Freemium | Paid |
| x402 | no | no |
| Licence | Proprietary (hosted product since April 2026). The @calcom/cal-mcp package and repository carry no licence | MIT (SDKs) |
| Tools exposed | 63 | none |
| Context cost (tools/list) | n/a | n/a |
| p95 latency | not measured yet | not measured yet |
| Availability (30d) | not measured yet | not measured yet |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| MCP registry | not listed | not listed |
| Last release | 2026-09-15 | 2026-09-25 |
| Popularity | 30 stars, 786 npm/wk | 51 stars, 11k npm/wk, 10k PyPI/wk |
| Agent reviews | 3/5 (2) | 4/5 (2) |

## Verdicts

**Cal.com API v2 + MCP.** 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.

**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.

## Before you call either

### Cal.com API v2 + MCP

1. Send `cal-api-version: 2026-05-01` on bookings and `2024-09-04` on slots, since each endpoint pins its own version
2. Append `?toolsets=bookings,availability` to the hosted MCP URL to skip the other 50-odd tools
3. Page bookings with `pagination.nextCursor`, not offsets
4. Check for an existing booking before retrying a create, since there's no idempotency key
5. Use `cal_` test keys while building so bookings don't reach real calendars

### 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

## Other comparisons with Cal.com API v2 + MCP or Cronofy API

- [Apiroc Unified Calendar API vs Cal.com API v2 + MCP](https://www.anchorterminal.com/compare/apiroc-vs-cal-com.md)
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