# Square, Microsoft Bookings, Acuity and SimplyBook.me APIs, and Reserve with Google – Tiempo > The APIs of booking software businesses already use (Square Appointments, Microsoft Bookings, Acuity, SimplyBook.me) compared with building your own platform on Tiempo, plus what Reserve with Google needs. Source: https://tiempo.one/docs/vs-business-booking-apis Checked against each product’s own docs on 6 October 2026. Square Appointments, Microsoft Bookings, Acuity and SimplyBook.me are complete booking products for a business: a calendar, a booking page, payments and reminders, with an API on the side. Their APIs let you integrate _with a business that already uses them_, through that business’s own account and subscription. That’s the right tool for an add-on (a marketing app for Square sellers, say). It’s the wrong foundation for your own booking platform, where you want the product, the brand and the customer relationship, and only need someone else to run the schedule. That’s Tiempo’s job. ## At a glance Tiempo Square Microsoft Bookings Acuity SimplyBook.me Each business needs Nothing: you create its account A Square seller account (writes need a paid plan) A Microsoft 365 business subscription An Acuity subscription A SimplyBook.me account Built for Platforms you build Square sellers Microsoft 365 organisations Acuity customers Service businesses; white-label resellers Rooms and equipment via the API Resources Read-only on segments Not documented Not documented Listed as a feature Double booking Refused under a lock Buyer-level apps can’t; seller-level apps can Not documented Validated unless admin Not documented Webhooks Signed, every change booking.created / updated None for Bookings Signed Callback URL Payments, reminders, booking pages Yours Included Included Included Included Each product’s column reflects its own documentation on the date above. See the sources at the end. ## Square Bookings API Bookings in a Square seller’s Appointments calendar, alongside Square’s payments, customers and catalogue. Writing at seller level needs the seller on a paid Appointments plan, and the API can’t create team members or make them bookable. Seller-level apps can create double bookings and bookings outside hours; buyer-level apps can’t. Choose it to build for Square sellers. ## Microsoft Bookings (Graph) Graph’s Bookings API manages booking businesses, staff, services and appointments in a Microsoft 365 tenant, with Teams meetings and group appointments. Bookings isn’t among Graph’s resources with change notifications, so there are no webhooks. Choose it inside organisations that run on Microsoft 365. ## Acuity Scheduling A mature scheduling product (now part of Squarespace) with classes, packages, payments, intake forms and signed webhooks. Its API acts on one Acuity account, or many through OAuth, each with its own subscription; staff are “calendars”. Choose it to extend businesses that use Acuity. ## SimplyBook.me A modular booking product with classes, recurring services, resources, locations, payments and a Reserve with Google integration, priced by bookings per month. It also runs a white-label programme where partners manage client accounts from one admin. Choose it if you want a ready-made booking product under your brand rather than your own. ## Reserve with Google Reserve with Google is a channel rather than a booking system: it puts a “Book” button on Search and Maps. For appointments, Google’s integrations list now offers **Redirect**: the button sends the customer to your platform’s booking page for that business. To join, you apply as a partner, then upload daily feeds of businesses, booking links and services, and pass a sandbox and a production review. The real-time booking-server integration is documented for other programmes, offered on a limited basis. A platform on Tiempo qualifies the same way any booking platform does: Tiempo answers availability and places bookings behind your booking page; the partnership and feeds are yours. ## Where Tiempo fits Tiempo is for building your own booking product for many businesses, without each business subscribing to anything. It does the scheduling (resources, holds, conflicts, classes, series) and nothing your product should own. Start with the [quickstart](https://tiempo.one/docs/quickstart) or a [use-case guide](https://tiempo.one/docs/salons-and-barbers). ## Sources - [Square Bookings API: what it is](https://developer.squareup.com/docs/bookings-api/what-it-is) - [Square Bookings API: get ready](https://developer.squareup.com/docs/bookings-api/get-ready-to-use-the-api) - [Square Appointments pricing](https://squareup.com/us/en/appointments/pricing) - [Microsoft Graph Bookings API overview](https://learn.microsoft.com/en-us/graph/api/resources/booking-api-overview?view=graph-rest-1.0) - [Microsoft Graph change notifications](https://learn.microsoft.com/en-us/graph/api/resources/change-notifications-api-overview?view=graph-rest-1.0) - [Acuity: create appointments](https://developers.acuityscheduling.com/reference/post-appointments.md) - [Acuity webhooks](https://developers.acuityscheduling.com/docs/webhooks.md) - [SimplyBook.me llms.txt](https://simplybook.me/llms.txt) - [SimplyBook.me white-label programme](https://simplybook.me/en/white-label-partner-program) - [Google Actions Center integrations](https://developers.google.com/actions-center/verticals) - [Appointments Redirect overview](https://developers.google.com/actions-center/verticals/appointments/redirect/overview) - [Appointments Redirect feeds](https://developers.google.com/actions-center/verticals/appointments/redirect/integration-steps/feeds) 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)