Head to head · Calendar access · October 2026 research run

Cronofy API vs Truto Unified Calendar API

Cronofy API scores 67.5 (B) on agent readiness against Truto Unified Calendar API's 60.4 (C), and leads in 6 of 7 scored categories. Truto Unified Calendar API leads on schema & documentation. Both do calendar access.

Best calendar and scheduling APIs for AI agents · All 118 scheduling comparisons

Which one, for what

Cronofy API B

Best for Products that schedule across many people and rooms with strict data residency, especially in the UK and EU.

Ahead on

  • Reliability, 95 against 77
  • Agent ergonomics, 76 against 71
  • Security & auth, 60 against 52
  • Payments & pricing, 30 against 20
  • Maintenance & community, 71 against 50
  • Transparency & trust, 72 against 61

Also in its favour

  • A hosted endpoint, with nothing to install

Watch for

Production pricing starts at $819 a month billed yearly

Truto Unified Calendar API C

Best for Software companies that need their product's agent to read and book across customers' Google, Outlook, Cal.com and Calendly accounts.

Ahead on

  • Schema & documentation, 75 against 58

Watch for

Priced from $999 per connector a year with a demo-led sandbox

Why the edge

Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.

Maintenance & community Cronofy API +21

Cronofy API 71

Cronofy's UI Elements, the JavaScript components it publishes for its API, carry a dated changelog in the docs with three code releases in October 2026, 1.68.0 (15 October, Romanian language support), 1.68.1 (22 October, the Availability Rules element now encodes rule IDs in its request) and 1.68.2 (28 October, Date Time Picker keyboard and screen reader support), so the last code release is within 30 days (30). pycronofy 2.1.2 (30 October) and 2.1.1 (25 September) change only packaging, 2.1.0 (8 May) only replaces the pytz dependency with the standard library, and cronofy-node's newest tag, v3.8.4 (15 September 2025), bumps axios. In the 90 days from 4 August, the three UI Elements releases and the two pycronofy packaging releases, counted half (20, was 5). Support through the docs, support pages and support@cronofy.com, and cronofy-node merged an outside docs pull request on 7 October; the API changelog can't be read (5). SDKs exist in several languages but most are slow-moving, Node last tagged v3.8.4 on 15 September 2025 and Ruby last tagged in 2023 (8). CI on the Node and Python SDKs, with Python 3.15 added on 30 October 2026 (8). 30+20+5+8+8 = 71.

Truto Unified Calendar API 50

No API changelog, so the last API change can't be dated; the official @truto/truto-link-sdk was published as 1.3.5 on 26 October 2026, which we take as the latest dated release (20 of 30, since it is the connection widget, not the calendar API). Six Link SDK versions since 8 August (10 of 20, for the same reason). Support through Slack on paid plans, with no public tracker (5 of 15). A CLI and the Link SDK are official, with no API client (10 of 15). Package health not checked (5 of 10). 20 + 10 + 5 + 10 + 5 = 50.

Reliability Cronofy API +18

Cronofy API 95

Atlassian Statuspage at status.cronofy.com with the API, Scheduler, Meeting Agents and each calendar provider as components (20). history.atom shows nothing touching the service from 4 August to 2 November 2026; its one post in the window, on 22 October, says Cronofy is unaffected by two PHP vulnerabilities. The 7 July Event Triggers incident in the US data centre left the window, so a clean record (30, was 20). 50 requests a second and 500 in any 60 seconds by default (15). 429 documented with advice to stop requests temporarily, but no Retry-After or backoff figures. Event writes are upserts keyed on your event_id, so a repeat updates rather than duplicates (10). 99.99% uptime guarantee on Emerging and Growth, and an API SLA policy page (10). The API is GA, and the MCP server page no longer carries an early-access label but warns the standard is likely to change (10). 20+30+15+10+10+10 = 95.

Truto Unified Calendar API 77

Graded as a hosted service on the Unified Calendar API. Better Stack status page with components for api.truto.one health, ping and link-token endpoints and the static IP proxy, with incident history (20). The feed lists "APIs and Dashboard are down" on 29 October 2026 and delayed sync jobs and webhooks on 1 November, which counts as one major outage (10). Truto's own limit is 50 requests every 10 seconds per integrated account, in front of each vendor's (15). A vendor 429 comes back with Retry-After and normalised ratelimit-limit, -remaining and -reset headers, with no idempotency guidance for creates (12 of 15). The Enterprise plan lists an SLA guarantee (10). Generally available (10). 20 + 10 + 15 + 12 + 10 + 10 = 77.

Schema & documentation Truto Unified Calendar API +17

Cronofy API 58

No OpenAPI or other machine-readable contract found (0). llms.txt with about 35 to 40 links and Markdown copies of pages (10). Reference pages explain each parameter and spell out provider differences, such as Exchange and Office 365 taking only the start time zone (17). Required parameters, types and limits (such as 1,024 characters for summary) on each page (12). Examples on every endpoint, and an error page covering 400 to 500 with 422 bodies that carry a machine-readable key (14). /v1 in the path. The changelog at changelog.cronofy.com is on a host whose robots.txt disallows every agent but a list of search crawlers, so the 1 October reading of it (undated entries, years old) is struck and it is unread (5, on path versioning alone).

Truto Unified Calendar API 75

An OpenAPI specification is linked from the RFC 9727 API catalogue, but the file timed out and was not read, so it is credited as published and unverified (20 of 25). llms.txt and a Markdown sibling for every page (10). Parameter descriptions say what each does and what it falls back to, such as end_time defaulting to the month of start_time (15 of 20). Types, required marks and allowed values such as focus_time and out_of_office (13 of 15). One documented error shape with provider and Truto fields; few request examples on the reference pages read (12 of 15). Deprecated admin endpoints are marked, but no API changelog was found (5 of 15). 20 + 10 + 15 + 13 + 12 + 5 = 75.

Transparency & trust Cronofy API +11

Cronofy API 72

Closed service with terms naming Cronofy Limited (company 07878590) under English law, and MIT-licensed SDKs (15). The data management policy gives numbers. Third-party events kept 30 days after the last authorisation ends, managed events 90 days, application logs up to 90 days, backups 7 days in-region, and Aurora with KMS at rest (26). No deprecation policy found, only one note that available_periods stays supported (5). Six data centres with no personal data moving between them, but we found no sub-processor list (12).

Truto Unified Calendar API 61

Closed service under terms naming Yin Yang Inc. (15 of 30). Truto says it stores no customer data and calls vendors live, logs are kept 30 or 90 days by plan, data is kept 15 days after termination, and a DPA is public (25 of 30). Deprecated admin endpoints are marked with no policy or dates (6 of 20). Enterprise customers can choose a data region and tokens can be stored regionally; no subprocessor list was found (8 of 20). 15 + 25 + 6 + 8 = 54.

Payments & pricing Cronofy API +10

Cronofy API 30

No x402, MPP or L402 (0). Plan prices and per-account overage ($1.39 and $0.69 an account a month) published without login (20). A free developer account exists, but the pricing page doesn't say whether a card is needed (10). Browser signup, and production needs a paid plan (0).

Truto Unified Calendar API 20

No x402, MPP or L402 (0). Plan prices per connector a year are public, with unlimited calls (10). A free 30-day sandbox is given after a work-email request reviewed within a business day (10 of 20). A person requests access or books a demo (0). 0 + 10 + 10 + 0 = 20.

Security & auth Cronofy API +8

Cronofy API 60

Per-user OAuth with fine scopes, including free_busy alone, read_only, and delete_event separate from create_event. Application calls and the single-tenant MCP use the application's client_secret as a Bearer token, which reaches every connected account (25). An agent can be limited to free/busy or to events it created (only_managed), but nothing confirms deletes (17). Event titles and descriptions from third parties come back with no injection guidance (0). No operator audit log found (0). ISO 27001, 27018 and 27701, SOC 2 Type 2 and a public bug bounty policy. No security.txt, per the 30 September check (18).

Truto Unified Calendar API 52

API tokens are per environment and sent as Bearer headers; no scopes or expiry for them were found (20 of 30). Per-account MCP servers can be limited to read methods or tags and set to expire, and the customer's connection form can restrict access to specific resources, but the REST token reaches every integrated account in its environment (14 of 20). Event titles, descriptions and attendee text from outside parties pass through, and no prompt-injection guidance was found (0). Plans keep request logs 30 or 90 days (10 of 15). SOC 2 is stated in a 2023 blog post, with no trust page, security.txt or disclosure policy found (8 of 20). 20 + 14 + 0 + 10 + 8 = 52.

Score by category

CategoryWeight this runCronofy APITruto Unified Calendar APIEdge
Reliability16%209577Cronofy API +18
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.25875Truto Unified Calendar API +17
Agent ergonomics13%16.27671Cronofy API +5
Security & auth14%17.56052Cronofy API +8
Payments & pricing10%12.53020Cronofy API +10
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87150Cronofy API +21
Transparency & trust7%8.87261Cronofy API +11
Negative events≤1500
TotalB 67.5/100C 60.4/100

Facts side by side

FactCronofy APITruto Unified Calendar API
KindHTTP APIHTTP API
VendorCronofyYin Yang Inc.
Hosted endpointhttps://api.cronofy.comno (local only)
TransportsHTTP, Streamable HTTP
AuthOAuth or keyAPI key
PricingPaidPaid
x402nono
LicenceMIT (SDKs)none
Read-only variant documentednono
llms.txtyesyes
Last release2026-10-302026-10-26
Terms last updatedno date givenno date given
Privacy policy last updatedno date given2024-10-19
Customer content may train modelsnot found in the textnot found in the text
Terms restrict automated accessnot found in the textnot found in the text
Terms restrict benchmarkingyesnot found in the text
Terms or service can change without noticenot found in the textnot found in the text
Arbitration or class-action waivernot found in the textyes
Popularity51 stars, 11k npm/wk, 10k PyPI/wknone
Agent reviews4/5 (2)none

How the scores have moved

Verdicts

Cronofy API

OAuth scopes as narrow as free_busy, with delete_event separate from create_event, a 99.99% uptime guarantee and no incident touching the service since July 2026. Production pricing starts at $819 a month billed yearly, and the Python and Node SDKs' recent releases only change packaging or dependencies.

Truto Unified Calendar API

Truto's calendar API is well documented for agents, with Markdown docs, field exclusion, normalised rate-limit headers and errors that name the failing side, across Google, Outlook, Cal.com and Calendly. It is sold from $999 a connector a year through a demo, had an API outage on 29 October 2026 and has no public changelog.

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

Truto Unified Calendar API

  1. Pass integrated_account_id on every call; the token alone reaches nothing
  2. Call the meta endpoint for the method first to see which filters the vendor supports
  3. Set truto_ignore_remote_data=true and list fields in truto_exclude_fields to keep responses small
  4. On 429 wait for Retry-After; stay under 50 requests every 10 seconds per integrated account
  5. Set expand_recurring=true when the task needs each instance of a repeating event

Questions

Which is better for AI agents, Cronofy API or Truto Unified Calendar API?

Cronofy API scores 67.5 (B) on agent readiness against Truto Unified Calendar API's 60.4 (C), and leads in 6 of 7 scored categories. Truto Unified Calendar API leads on schema & documentation.

Do Cronofy API and Truto Unified Calendar API need an API key?

Cronofy API takes an API key or an OAuth sign-in. Truto Unified Calendar API needs an API key.

Can an agent call Cronofy API and Truto Unified Calendar API without installing anything?

Cronofy API has a hosted endpoint at https://api.cronofy.com. No hosted endpoint is listed for Truto Unified Calendar API.

Other comparisons with Cronofy API or Truto Unified Calendar API

Machine-readable

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