Are there any free calendar APIs? A 2026 pricing comparison

When it comes to free calendar APIs, you generally have two options:

1. Provider-native APIs. The Google Calendar API and the Microsoft Graph calendar endpoints charge nothing for standard use. However, integrating with these calendars for meeting recording is time-consuming and involves accounting for many edge cases related to event changes.

2. Unified (multi-provider) APIs. These solutions work across calendars on Microsoft and Google and handle much of the complexity of scheduling meeting recordings. However, they generally require payment. The only exception is Recall.ai, which is a unified calendar API that is completely free.

Note: If you need users to book meetings and find availability, you will need a scheduling API, which is a separate topic.

Free calendar APIs compared (October 2026)

Prices are list prices as published in October 2026; vendor pages change, so confirm before budgeting.

Provider-native APIs: free, and you own the integration

The cost of native APIs is the integration layer. Each provider needs its own OAuth app and verification, its own token refresh and webhook renewal logic, and its own handling of recurrence exceptions, time zones and all-day events. There is a lot of complexity involved in using calendar data to schedule meeting recordings, which we cover below.

What a calendar integration for meeting recording has to do

Reading a calendar is the easy part. However, a recording product has to turn a stream of calendar changes into a reliable decision about which meetings to join, when, and with what context attached. In practice that is many pieces of logic, and each one has many edge cases that show up in production.

1. Connect the calendar with the smallest possible scope. Each user authorizes your app once via OAuth for Google or Microsoft. Ask for read-only calendar scopes; you never need to write events to record them, and read-only scopes clear Google’s sensitive-scope verification faster. You’ll need to handle situations where the user revokes access, changes their password (which invalidates Microsoft tokens), or connects a second calendar on the other provider. Store refresh tokens encrypted and plan for them to expire or be revoked without warning.

2. Sync events, then keep syncing incrementally. The first sync with a calendar pulls a window of events (typically the next few weeks). After that you need to poll for the deltas, not full re-pulls of the calendar. Google’s syncToken and Microsoft Graph’s delta queries return only what changed from the original calendar events, so you can understand the current state of the calendar from that data.

   When doing this, it’s important to watch out for recurring meetings: you’ll have to add exceptions for every instance someone moved or cancelled. For example, you need to recognize that if someone moves a weekly call on Tuesdays at 3pm to 4pm for just one week, it’s not a change to the entire series. Varying time zones and all-day events are other common sources of issues that lead bots to show up at the wrong time.

3. Receive change notifications and survive missing them. Polling thousands of calendars every minute burns provider quota and still lags. Both providers push change notifications, but Google watch channels expire after about a week, and Microsoft Graph event subscriptions after about three days. Both must be renewed before they lapse.

   Notifications can also arrive out of order or be dropped, so you’ll need to run a renewal job and a periodic reconciliation sync. When you do miss a window, you can have a bot that joins a cancelled meeting or misses a rescheduled one.

4. Find the meeting and the platform. The join link lives in different places: Google’s conferenceData for Meet, Graph’s onlineMeeting for Teams, and the description, location or body field for Zoom, Webex and everything else. You need platform-specific link parsing (including passcodes embedded in Zoom URLs), a way to handle events with no link at all, and a rule for events with more than one. The platform you detect decides which bot you send and how early it should join.

5. Decide whether to record. You’ll need to include per-user logic about which meetings should be recorded. Common rules include only recording meetings with external attendees, only meetings the user has accepted, only events whose title matches a pattern ("Interview", "Customer"), or never recording events marked private.

   The inputs are attendee domains, RSVP status, organizer, visibility and title, so the sync layer has to keep all of them current, and a user changing their preferences has to re-evaluate every upcoming event. You will also have to deal with deduplication: when four teammates all have the same customer call on their calendars, you want one bot in the room, not four. That means having a stable meeting identity across users’ copies of the event (the join URL plus start time usually works) and a shared key your scheduler respects.

6. Schedule the bot and attach the context. Once an event passes the rules, the scheduler creates the bot ahead of the start time, moves it when the event moves, and removes it when the event is cancelled or the user declines.

   After the meeting, the calendar data is what makes the recording useful: title, organizer, attendee list and emails let you name the file, map email addresses to speakers in the transcript, and show the user which meeting a recording belongs to.

Unified calendar APIs: where "free tier" usually means sandbox

A unified API connects to Google and Microsoft Outlook with one integration, and takes on token refresh, webhook renewal and recurrence normalization for you. This saves a considerable amount of engineering time, but for that reason, most unified API vendors other than Recall.ai do not offer free plans in production.

Nylas. Nylas’s free plan covers 5 connected email and calendar accounts, and is only intended for development and testing. Paid plans start at $15/month for 10 calendar integrations but companies will need to speak to Nylas’s sales team to integrate with calendars at scale.

Cronofy. Cronofy does not have a free production tier. New applications get a development environment, and billing starts when the app is verified for production. Plans start at $819/month for up to 500 calendar integrations, and go up to $2,399/month for up to 3,000 calendar integrations. While Cronofy is the strongest option for scheduling (round-robin, resource booking, real-time availability across providers), it is the most expensive to start.

Recall.ai Calendar API. Recall.ai’s calendar API is free in production, with no cap on how many user calendars you can connect to. Recall.ai’s API integrates with Google Calendar and Microsoft Outlook, delivers update and delete notifications by webhook, and can automatically schedule a meeting bot for events that match rules you define. Recall.ai’s calendar API also offers deduplication so several users sharing one meeting don’t produce several bots. It is specifically built for helping products that work with meeting data schedule recordings and get information from user calendars. If your main requirement is event creation or booking, use a native API or a scheduling platform instead.

Holiday APIs are sometimes called calendar APIs, but aren’t the same thing

Holiday and date-data APIs (Nager.Date, OpenHolidays, Calendarific, Abstract) return public holidays and observances by country. They are mostly free with request caps (Calendarific: 500 calls/month free; Nager.Date: free with no key, sponsorship requested for commercial use). However, while these solutions show up in searches for "free calendar API,” they are specifically designed for programmatically tracking holidays, not for working with meeting recordings or individual users’ calendars.

Which free calendar API should you use?

If you’re building a product that works with meeting data, Recall.ai’s Calendar API is the only free option that covers both providers in production and the only one that connects calendar events directly to a meeting bot. It handles the sync, notifications, link parsing, recording rules, deduplication and bot scheduling described above, with no cap on connected calendars. This is a huge time-saver as opposed to building from scratch with a native API, as Recall.ai’s calendar integration is designed specifically for the meeting recording use case.