Cal.com Companion

Your scheduling companion — in your pocket or your browser.

Website · App Store · Google Play · Chrome Web Store

---

Cal.com Companion lets you manage your Cal.com schedule from anywhere. It ships as a mobile app (iOS & Android), a set of browser extensions (Chrome, Firefox, Safari, Edge), and home-screen widgets — all from a single codebase.

Mobile App

A native companion app built with Expo and React Native.

• Bookings — View, cancel, reschedule, add guests, and mark no-shows
• Event Types — Browse and edit event types including duration, recurrence, limits, and availability
• Availability — Manage schedules, working hours, and date overrides
• Widgets — Home-screen widgets for iOS (WidgetKit) and Android show your upcoming bookings at a glance
• Dark mode — Full light/dark theme support that follows your system preference
• OAuth — Secure sign-in via Cal.com OAuth with PKCE

Browser Extensions

A cross-browser extension built with WXT that brings Cal.com into the pages you already use.

• Sidebar — Click the Cal.com icon in your browser toolbar to open a sidebar with your full bookings, event types, and availability
• Gmail integration — A Cal.com button appears in the Gmail compose toolbar so you can insert a scheduling link directly into an email
• LinkedIn integration — A Cal.com button is injected into the LinkedIn messaging composer for quick link sharing
• Google Calendar no-show — Adds a "No Show" toggle next to attendees in Google Calendar event popups for Cal.com bookings
• Supported browsers — Chrome, Brave, Firefox, Safari, and Microsoft Edge

Tech Stack

Layer	Technology
Mobile app	Expo (React Native) with Expo Router
Styling	NativeWind (Tailwind CSS for React Native)
Browser extension	WXT (next-gen web extension framework)
Data fetching	TanStack Query with persistent cache
iOS widget	SwiftUI + WidgetKit
Android widget	react-native-android-widget
Auth	Cal.com OAuth 2.0 with PKCE

Getting Started

Prerequisites

• Node.js (v18+)
• Bun (recommended) or npm
• For mobile development: Xcode (iOS) or Android Studio (Android)

Install dependencies

bun install

Environment

Copy the example env file and fill in your Cal.com OAuth credentials:

cp .env.example .env

Run the mobile app

# iOS
bun run ios

# Android
bun run android

# Web (Expo)
bun run web

Run the browser extension

# Dev mode (Chrome, hot reload)
bun run ext

# Build for a specific browser
bun run ext:build-chrome
bun run ext:build-firefox
bun run ext:build-safari
bun run ext:build-edge

# Build all browsers
bun run ext:build-all

Production builds (for store submission) use the -prod variants which point to https://companion.cal.com:

bun run ext:build-chrome-prod
bun run ext:zip-chrome-prod

Project Structure

├── app/                  # Expo Router screens (tabs, modals, sheets)
├── components/           # Shared React Native components
├── extension/            # Browser extension source (WXT)
│   ├── entrypoints/      # Background script & content script
│   ├── lib/              # Gmail, LinkedIn, Google Calendar integrations
│   └── public/           # Extension icons & static assets
├── hooks/                # Custom React hooks
├── services/             # Cal.com API client & OAuth service
├── contexts/             # React context providers (Auth, Query, Toast)
├── widgets/              # Android home-screen widget
├── targets/widget/       # iOS WidgetKit target (SwiftUI)
├── utils/                # Shared utilities
├── config/               # Cache configuration
├── constants/            # Colors, timezones
└── types/                # Shared TypeScript types

Scripts

Command	Description
bun run start	Start the Expo dev server
bun run ios	Run on iOS simulator
bun run android	Run on Android emulator
bun run web	Run in the browser via Expo
bun run ext	Start extension dev server (WXT)
bun run ext:build-all	Build extension for all browsers
bun run typecheck	Type-check the mobile app
bun run typecheck:extension	Type-check the browser extension
bun run lint	Lint with Biome
bun run format	Format with Biome
bun run check:ci	Run Biome CI checks

Contributing

This repo uses Biome for linting and formatting, enforced via Husky pre-commit hooks. Before submitting a PR, make sure your changes pass:

bun run check:ci
bun run typecheck:all

Links

• Cal.com
• Cal.com Companion landing page
• Chrome Web Store
• Documentation