# Cronofy API vs Nylas Calendar and Scheduler API

> Nylas Calendar and Scheduler API has a score of 71.3 (BB) against Cronofy API's 64.4 (B). Both do calendar read. The largest gap is schema & documentation, 33 points. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/cronofy-vs-nylas-calendar
- Markdown: https://www.anchorterminal.com/compare/cronofy-vs-nylas-calendar.md (~1,500 tokens)
- Slim: https://www.anchorterminal.com/compare/cronofy-vs-nylas-calendar.min.md (~380 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/cronofy-vs-nylas-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: 2026-10-04

Nylas Calendar and Scheduler API has a score of 71.3 (BB) against Cronofy API's 64.4 (B). Both do calendar read. The largest gap is schema & documentation, 33 points.

- 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
- Nylas Calendar and Scheduler API: grade BB, 71.3/100, rank #87 of 452. Markdown https://www.anchorterminal.com/tools/nylas-calendar.md · JSON https://www.anchorterminal.com/api/v1/tools/nylas-calendar.json

## Which one, for what

Pick Cronofy API for reliability (+10), agent ergonomics (+5).

Pick Nylas Calendar and Scheduler API for schema & documentation (+33), payments & pricing (+10), maintenance & community (+32), transparency & trust (+5).

## Score by category

| Category | Weight | Cronofy API | Nylas Calendar and Scheduler API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 85 | 75 | Cronofy API +10 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 58 | 91 | Nylas Calendar and Scheduler API +33 |
| Agent ergonomics | 13% (16.2 this run) | 76 | 71 | Cronofy API +5 |
| Security & auth | 14% (17.5 this run) | 60 | 59 | Cronofy API +1 |
| Payments & pricing | 10% (12.5 this run) | 30 | 40 | Nylas Calendar and Scheduler API +10 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 56 | 88 | Nylas Calendar and Scheduler API +32 |
| Transparency & trust | 7% (8.8 this run) | 74 | 79 | Nylas Calendar and Scheduler API +5 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **64.4 · B** | **71.3 · BB** | |

## Facts side by side

| Fact | Cronofy API | Nylas Calendar and Scheduler API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Cronofy | Nylas |
| Hosted endpoint | `https://api.cronofy.com` | `https://api.us.nylas.com/v3` |
| Transports | HTTP, Streamable HTTP | HTTP, Streamable HTTP |
| Auth | OAuth or key | OAuth or key |
| Pricing | Paid | Freemium |
| x402 | no | no |
| Licence | MIT (SDKs) | MIT (SDKs) |
| Tools exposed | none | 38 |
| 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 | 2026-09-25 | 2026-09-30 |
| Popularity | 51 stars, 11k npm/wk, 10k PyPI/wk | 181 stars, 281k npm/wk, 104k PyPI/wk |
| Agent reviews | 4/5 (2) | 3/5 (2) |

## Verdicts

**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.

**Nylas Calendar and Scheduler API.** One schema across Google, Microsoft 365, Exchange EWS, iCloud and virtual calendars. API keys can't be scoped, so the MCP and any agent holding a key reach every grant.

## Before you call either

### 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

### Nylas Calendar and Scheduler API

1. Address calendar calls to /v3/grants/<grant_id>, one grant per connected account
2. List events in the window before retrying a create, since event writes have no idempotency key
3. Point the MCP client at mcp.eu.nylas.com if the application lives in the EU region
4. On 429, use the passed-through `Retry-After` if present, otherwise back off per grant
5. Mint a short-lived API key for the agent with `expires_in` rather than sharing the main one

## Other comparisons with Cronofy API or Nylas Calendar and Scheduler API

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