Privacy

Privacy Policy

Callisto is a menu bar app for macOS that shows and manages your meetings from Google Calendar. This policy explains what the app accesses, where data is stored, and how it is used.

Last updated June 1, 2026

Overview

Callisto is designed as a local-first macOS app. It does not require a Callisto account, and the app does not operate a separate backend service for your calendar data. Calendar access is requested through Google OAuth so the app can show your upcoming meetings and let you manage meeting-related calendar actions from the menu bar.

Information Callisto Accesses

When you connect a Google account, Callisto requests access to your Google profile and Google Calendar data. Depending on the permissions you grant, this may include:

  • Your Google account identifier, email address, and display name.
  • Your calendar list, calendar names, colors, time zones, and calendar visibility metadata.
  • Calendar events for the local sync window, including titles, descriptions, times, locations, attendees, reminders, attachments metadata, recurrence data, conference links, organizer details, RSVP status, and event links.
  • Event changes you explicitly make in Callisto, such as RSVP updates, event deletion, or removing an event from your own calendar view.

Google OAuth Scopes

Callisto currently requests these Google OAuth scopes:

  • https://www.googleapis.com/auth/calendar.readonly, used to read your calendar list and upcoming calendar events.
  • https://www.googleapis.com/auth/calendar.events, used only when you perform event actions such as RSVP updates or deleting/removing events.
  • https://www.googleapis.com/auth/userinfo.email and https://www.googleapis.com/auth/userinfo.profile, used to identify and label the Google account you connected.

How Callisto Uses Google Data

Callisto uses Google Calendar data to provide the app's visible meeting features: showing your upcoming events in the macOS menu bar, opening meeting links, filtering visible calendars and accounts, syncing event data, and applying meeting actions you choose. Callisto does not use Google user data for advertising, credit decisions, surveillance, or unrelated product features.

Callisto's use and transfer of information received from Google APIs will adhere to the Google API Services User Data Policy , including the Limited Use requirements.

Local Storage

OAuth access and refresh tokens are stored only in the macOS Keychain. Account metadata, calendar metadata, event data, attendees, reminders, and attachment metadata are stored locally on your Mac using SwiftData. App preferences, such as sync interval and display options, are stored in UserDefaults.

Data Sharing

Callisto sends Google API requests directly from your Mac to Google in order to authenticate, refresh tokens, read calendars and events, and apply event changes you request. Callisto does not sell your personal data and does not transfer your Google Calendar data to advertising platforms, data brokers, or other third parties.

The public website is hosted on Cloudflare Workers static assets. Downloads and app update metadata are served through GitHub releases. Those providers may process ordinary connection information, such as IP address, user agent, timestamps, and requested URLs, under their own terms and privacy policies.

Analytics and Tracking

Callisto does not include in-app advertising SDKs, third-party analytics SDKs, or behavioral tracking code. The website does not set application cookies or include client-side analytics code in this repository.

Security

Calendar data is transmitted over HTTPS through Google's APIs. OAuth tokens are stored in the macOS Keychain with Data Protection Keychain support and are not stored in SwiftData or UserDefaults. Local app data remains on your Mac unless you choose to use macOS, Google, GitHub, or other system-level services that sync, back up, or process data independently of Callisto.

Retention and Deletion

Callisto keeps local account, calendar, event, and settings data while you use the app. Removing a Google account from Callisto deletes that account's OAuth tokens from the macOS Keychain and removes the account, calendars, and events for that account from the local app database. You can also revoke Callisto's Google access from your Google Account permissions page.

Children

Callisto is not directed to children under 13 and should not be used by anyone who is not permitted to grant Google account access under applicable law and Google's terms.

Changes

This policy may be updated as Callisto changes. If Callisto materially changes how it accesses, uses, stores, or shares Google user data, the published policy will be updated before that new use is introduced.

Contact

For privacy questions or requests, contact the Callisto maintainers through GitHub Issues.