# Booking engine or calendar scheduling API? – Tiempo

> Tiempo compared with Cal.com, Calendly, Nylas and Cronofy: calendar APIs schedule people’s diaries; a booking engine runs many businesses’ staff, rooms, holds and classes.

Source: https://tiempo.one/docs/vs-calendar-apis

Checked against each product’s own docs on 6 October 2026.

Cal.com, Calendly, Nylas and Cronofy are good at one problem: finding a time in _people’s calendars_. Someone connects their Google or Outlook account, sets their hours, and others book meetings with them.

A booking platform for barbers, studios or clubs has a different problem. The businesses don’t live in Google Calendar; their availability is staff rotas, rooms, chairs and courts, kept by your platform. Bookings need holds while customers pay, “anyone available” across a team, classes with places, and the same rules for every business you onboard. That’s what Tiempo is for.

Neither is better in general. If your users’ diaries are the source of truth, use a calendar API. If your platform is the source of truth, use a booking engine.

## At a glance

Tiempo

Cal.com

Calendly

Nylas

Cronofy

Availability comes from

Schedules you set per resource

Users’ hours and calendars

Users’ hours and calendars

Connected calendars

Connected calendars, rules

Rooms, chairs, courts

Resources, first class

Not documented

Not documented

Room calendars or app-made calendars

With people in one query

Many businesses for one integrator

An account per business, made by API

Organizations (Platform’s managed users deprecated)

Each business’s own Calendly account

Grants per connected account

Per-user or organization connect

Holds that expire

Yes, 15 min by default

Slot reservations (5 min default)

Not documented

Placeholder until the organizer decides

Not documented

Classes with places

Sessions with seats

Seats per slot

Group events

Group meetings

Bookable events (beta)

Calendar sync

No

Yes

Yes

Yes

Yes

Hosted booking pages

No

Yes

Yes

Yes

Embedded scheduler

Each product’s column reflects its own documentation on the date above. See the sources at the end.

## Cal.com

Open-source scheduling with an API, embeddable components and hosted pages, calendar sync, payments, conferencing and reminders. It’s the natural choice for meeting scheduling inside a product, and you can self-host it.

For platforms, note that its “Platform” product (managed users, platform OAuth clients and webhooks) is marked deprecated in the API reference, and the React “Atoms” package is in maintenance mode. New integrations are pointed at API v2 with ordinary Cal.com accounts and OAuth. Pricing is per user.

## Calendly

The API sits on top of Calendly accounts: your app connects to users who each have their own Calendly subscription. Booking through the API (the Scheduling API) needs a paid plan, and the docs say there’s no endpoint to reschedule. Choose it when your users already live in Calendly.

## Nylas

A unified API over email, calendars and contacts, with Scheduler for booking pages. It re-checks a slot before booking. For rooms that aren’t in Google Workspace or Microsoft 365, its own cookbook has you give the room a calendar and apply business hours, capacity and conflict checks in your webhook handler. Choose it when you’re building on people’s mailboxes and calendars.

## Cronofy

Calendar infrastructure for software companies, and the most capable of the four for mixed availability: it can require a person and a room together in one query, and keeps hosted calendars for things without their own. Plans start at $819 a month (billed annually). Choose it for enterprise calendar sync, recruiting or sales scheduling.

## Where Tiempo fits

Tiempo has no calendar sync, booking pages, payments or reminders: your platform keeps those. It runs the schedule itself, for every business on your platform: resources and rotas, holds that lapse on their own, atomic “anyone available”, multi-resource services, classes and series, with locking so two customers never get the same slot.

See it in the [quickstart](https://tiempo.one/docs/quickstart), or read [how it compares with other booking engines](https://tiempo.one/docs/vs-headless-engines).

## Sources

-   [Cal.com API v2 reference (deprecated Platform section)](https://cal.com/docs/_llms/api-v2-reference.md)
-   [Cal.com Atoms introduction (maintenance mode)](https://cal.com/docs/atoms/introduction.md)
-   [Cal.com: reserve a slot](https://cal.com/docs/api-reference/v2/slots/reserve-a-slot.md)
-   [Cal.com pricing](https://cal.com/pricing)
-   [Calendly: create event invitee (Scheduling API)](https://developer.calendly.com/api-docs/calendly-api/scheduled-events/create-event-invitee.md)
-   [Calendly developer FAQ](https://developer.calendly.com/docs/getting-started/frequently-asked-questions.md)
-   [Nylas Scheduler](https://developer.nylas.com/docs/v3/scheduler/)
-   [Nylas: schedule resources with Agent Accounts](https://developer.nylas.com/docs/cookbook/calendar/schedule-resources-with-agent-accounts/)
-   [Nylas pricing](https://www.nylas.com/pricing/)
-   [Cronofy Availability API](https://docs.cronofy.com/developers/api/scheduling/availability/index.md)
-   [Cronofy pricing](https://www.cronofy.com/pricing)

The machine-readable description is at [/openapi.json](https://tiempo.one/openapi.json). Try calls in [Swagger UI](https://tiempo.one/swagger-ui.html).[Tiempo home](https://tiempo.one/)[Dashboard](https://tiempo.one/app)