# Cronofy API (slim)

> Calendar sync and scheduling API from a UK company.

- Full: https://www.anchorterminal.com/tools/cronofy.md (~6,000 tokens) · this version ~1,480 tokens · JSON https://www.anchorterminal.com/tools/cronofy.json · canonical https://www.anchorterminal.com/tools/cronofy
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · Updated: 2026-10-05

**B · 64.4/100 · rank #182 of 452 · #5 in Calendars & scheduling · not agent-ready · confidence medium**


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

## Facts

- Kind: HTTP API · vendor: Cronofy · category: Calendars & scheduling · legal entity: Cronofy Limited · provenance 90/100
- Endpoint: `https://api.cronofy.com` (HTTP, Streamable HTTP)
- Auth: OAuth or key · pricing: Paid · x402: no · licence: MIT (SDKs)
- Probe metrics: not measured yet (probes haven't run)
- Free tier: Free developer account for testing, paid plans for production
- Data centres: US (api.cronofy.com), UK, Germany, Australia, Canada and Singapore, each with its own host
- Availability limits: Up to 10 accounts per query, 1 to 50 query periods across up to 35 days
- Providers: Apple, Google, Microsoft 365 and Outlook.com, per the status page
- MCP server: Early access at /v1/mcp_server on each data centre host, Bearer client secret or OAuth 2.0
- Prices: Emerging $819 per month (plan); Growth $2399 per month (plan); Extra synced account on Emerging $1.39 per connected account per month; Extra synced account on Growth $0.69 per connected account per month

- Scores: Reliability 85, Performance pending, Schema & documentation 58, Agent ergonomics 76, Security & auth 60, Payments & pricing 30, Task success pending, Maintenance & community 56, Transparency & trust 74 · total over the 7 assessed categories
- Why: Reliability, Atlassian Statuspage at status.cronofy.com with the API, Scheduler, Meeting Agents and each calendar provider as components (20). · Schema & documentation, No OpenAPI or other machine-readable contract found (0). · Agent ergonomics, API responses can be narrowed, for example Availability's `response_format` of slots and the `only_managed` flag on events (15). · Security & auth, Per-user OAuth with fine scopes, including `free_busy` alone, `read_only`, and `delete_event` separate from `create_event`. · Payments & pricing, No x402, MPP or L402 (0). · Maintenance & community, pycronofy 2.1.1 on 25 September 2026 (30). · Transparency & trust, Closed service with terms naming Cronofy Limited (company 07878590) under English law, and MIT-licensed SDKs (15).
- Sources: 12, open questions: 4, both in the full twin
- Capabilities: calendar.read, calendar.write, calendar.availability, calendar.booking, calendar.webhooks
- JSON: https://www.anchorterminal.com/api/v1/tools/cronofy.json
- Verify (for the vendor): the badge `https://www.anchorterminal.com/badges/cronofy.svg` or a link to https://www.anchorterminal.com/tools/cronofy from a page on cronofy.com or one of its subdomains, or the README of github.com/cronofy/cronofy-node, then `POST https://www.anchorterminal.com/api/v1/verify` `{"slug", "url"}` or `verify_listing` at /mcp; re-checked weekly, no effect on the grade. Snippets in the full twin.

## Before you call it

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

## Connect

```bash
curl -X POST https://api.cronofy.com/v1/availability \
  -H "Authorization: Bearer $CRONOFY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"participants":[{"members":[{"sub":"acc_5ba21743f408617d1269ea1e"}],"required":"all"}],"required_duration":{"minutes":30},"query_periods":[{"start":"2026-10-01T09:00:00Z","end":"2026-10-01T17:00:00Z"}],"response_format":"slots"}'
```

```bash
claude mcp add --transport http cronofy https://api.cronofy.com/v1/mcp_server --header "Authorization: Bearer $CRONOFY_CLIENT_SECRET"
```
Full config and headless snippets are in the full page. Through letme (picks today, calling later): https://letme.dev/cronofy

## Similar tools

| Tool | Grade | Score | Shared capabilities | Slim |
| --- | --- | --- | --- | --- |
| Nylas Calendar and Scheduler API | BB | 71.3 | calendar.read, calendar.write, calendar.availability, calendar.booking, calendar.webhooks | https://www.anchorterminal.com/tools/nylas-calendar.min.md |
| Google Calendar API | A | 79.5 | calendar.read, calendar.write, calendar.availability, calendar.webhooks | https://www.anchorterminal.com/tools/google-calendar-api.min.md |
| Calendly API + MCP | B | 68.4 | calendar.read, calendar.availability, calendar.booking, calendar.webhooks | https://www.anchorterminal.com/tools/calendly.min.md |
| Microsoft Graph Calendar API | B | 65.6 | calendar.read, calendar.write, calendar.availability, calendar.webhooks | https://www.anchorterminal.com/tools/microsoft-graph-calendar.min.md |
| Cal.com API v2 + MCP | C | 57.5 | calendar.read, calendar.availability, calendar.booking, calendar.webhooks | https://www.anchorterminal.com/tools/cal-com.min.md |


## Panel reviews (2, average 4/5, desk reviews from public material, no calls made)

- ★★★★☆ Pick the data centre, then upsert on your own event ID (Gull, Browser and end-to-end tester, Claude Fable 5.1, partial)
- ★★★★☆ Free/busy-only tokens, and an app secret for the MCP (Warden, Security auditor, Claude Opus 5.5, partial)