SnapCal

A Chrome extension that captures a screenshot of any web page, uses Google Gemini AI to extract event details, and creates a Google Calendar event — all in a couple of clicks.

Features

• Screenshot-to-event — capture the visible tab and let Gemini parse the title, date, time, location, and description automatically.
• Review before adding — extracted details are shown in an editable form so you can tweak anything before it hits your calendar.
• Keyboard shortcut — press Ctrl+Shift+S (Windows/Linux) or Cmd+Shift+S (Mac) to snap and analyze instantly without opening the popup first.
• Configurable AI model — choose between Gemini 2.5 Flash (fast) and Gemini 2.5 Pro (more capable) in the options page.
• Timezone & duration defaults — set your preferred timezone and default event duration so new events are created with sensible values.

Prerequisites

• Node.js (v18 or later recommended)
• Google Chrome (or any Chromium-based browser that supports Manifest V3)
• Gemini API key — get one for free at Google AI Studio

Installation

1. Clone and build

git clone https://github.com/RogerMcKenzie/SnapCal.git
cd SnapCal
npm install
npm run build

This produces a dist/ folder containing the built extension.

2. Load the extension in Chrome

1. Open chrome://extensions in your browser.
2. Enable Developer mode (toggle in the top-right corner).
3. Click Load unpacked and select the dist/ folder.
4. The SnapCal icon will appear in your toolbar.

3. Add your Gemini API key

1. Right-click the SnapCal icon and choose Options (or click the gear icon inside the popup).
2. Paste your Gemini API key and choose your preferred model.
3. Optionally adjust the default event duration and timezone.
4. Click Save Settings.

4. Sign in with Google

Open the SnapCal popup and click Sign in with Google. This authorizes the extension to create events on your primary Google Calendar.

Usage

1. Navigate to a page that contains event information (a concert listing, meetup page, email, flyer, etc.).
2. Click the SnapCal toolbar icon (or use the keyboard shortcut).
3. Click Capture Screenshot — the extension takes a screenshot of the visible area.
4. Review the screenshot preview, then click Analyze with AI.
5. Gemini extracts the event details and populates an editable form.
6. Adjust any fields if needed, then click Add to Calendar.
7. Done — a link to the new Google Calendar event is displayed.

Development

Run a local dev server with hot-reload:

npm run dev

Then load the extension from the generated dist/ directory the same way as described above. Vite + CRXJS will hot-reload changes as you edit source files.

Project structure

src/
├── background.ts          # Service worker (keyboard shortcut handler)
├── types.ts               # Shared TypeScript interfaces
├── lib/
│   ├── calendar.ts        # Google Calendar API client
│   ├── extractor.ts       # Page text extraction & screenshot capture
│   ├── gemini.ts          # Gemini API client & event parsing
│   ├── storage.ts         # Extension settings (chrome.storage)
│   └── utils.ts           # Sanitization & validation helpers
├── popup/                 # Browser-action popup (React)
│   ├── App.tsx
│   ├── components/
│   └── ...
└── options/               # Options page (React)
    ├── Options.tsx
    └── ...

Scripts

Command	Description
npm run dev	Start Vite dev server with HMR
npm run build	Type-check and build for production
npm run typecheck	Run TypeScript type checking only

Permissions

SnapCal requests the following Chrome permissions:

Permission	Why
activeTab	Capture a screenshot of the current tab
scripting	Extract page text when needed
storage	Persist your API key and preferences
identity	Sign in with Google and manage Calendar tokens

Troubleshooting

• "Gemini API key not configured" — open the extension options and paste a valid API key.
• "Invalid Gemini API key" — double-check the key at Google AI Studio.
• "Rate limit exceeded" — wait a moment and try again; the extension retries automatically with exponential backoff.
• Calendar sign-in fails — make sure third-party cookies are not blocking accounts.google.com, or try signing in through Chrome's profile.

License

MIT — Copyright (c) 2026 RogerMcKenzie