Sidebrief for Kagi Summarizer

Summarize any web page using the Kagi Universal Summarizer, right from your browser sidebar. Available for Chrome and Firefox.

How It Works

Sidebrief opens a sidebar panel next to whatever page you're reading. Click the toolbar icon, use a keyboard shortcut, or right-click any link and a summary appears alongside the page. You can switch between a full summary and bullet-point key moments, change the summarization engine, or paste any URL to summarize a page you're not even on.

Note

Sidebrief uses each browser's native sidebar API. The Side Panel API on Chrome and sidebar_action on Firefox. Safari and Orion do not currently support a sidebar API for extensions, so versions for those browsers are not available yet. Orion has similar functionality built in already.

Features

• Sidebar interface: summaries appear in a side panel alongside the page you're reading
• Summary or Key Moments: toggle between a full summary and bullet-point key moments
• Paste any URL or text: summarize any page by URL, or paste text directly (requires API token)
• Summarize selected text: right-click highlighted text to summarize it (requires API token)
• Copy, Markdown, and Share: copy summaries as plain text or Markdown, or share via the native share sheet
• Keyboard shortcuts: open/close the sidebar, summarize, or get key moments without touching the mouse
• Quick settings: change engine, output language, text size, and font family from the sidebar header
• Customizable text: adjustable summary text size (12px–24px) with sans-serif, serif, monospace, and OpenDyslexic font options
• Theme colors: six accent color choices
• History: your last 10 summaries are saved locally so you can revisit them
• Light and dark theme: follows your system preference

Accessibility

Sidebrief is built with accessibility in mind. The sidebar and options page include full ARIA labeling for screen readers, keyboard-navigable controls, and live region announcements for dynamic content like loading states and copy confirmations. All interactive elements meet WCAG 2.1 AA contrast ratios in both light and dark themes, and touch targets meet minimum size guidelines. The extension also respects prefers-reduced-motion to disable animations, prefers-contrast: more for increased contrast, and Windows High Contrast Mode (forced-colors: active). Summary text size is adjustable from 12px to 24px, and font family is customizable with serif, monospace, and OpenDyslexic options.

Keyboard Shortcuts

Action	Default Shortcut
Toggle sidebar	Alt+Shift+B (⌥ Shift B on macOS)
Summarize current page	Alt+Shift+S (⌥ Shift S on macOS)
Key moments	Alt+Shift+K (⌥ Shift K on macOS)

Shortcuts can be customized in your browser's extension shortcut settings:

• Chrome: chrome://extensions/shortcuts
• Firefox: about:addons → gear icon → Manage Extension Shortcuts

Setup

1. Install the extension
2. Click the Sidebrief icon in your toolbar to open the sidebar
3. Summarize the current page or paste any URL

The Cecil engine works for free if you're signed into kagi.com. For paid engines (Agnes, Muriel) and text summarization, add your API token in the extension settings.

Get an API token at kagi.com/settings/api. See the Summarizer API docs for pricing and usage details.

Installing Sidebrief

Sidebrief is available for manual download and installation. Store listings coming soon.

For Chrome

Download the latest release and unzip it. Navigate to chrome://extensions/ and enable "Developer mode" using the toggle in the top right corner. Click "Load unpacked" and select the unzipped folder.

For Firefox

Download the latest release and unzip it. Navigate to about:debugging#/runtime/this-firefox and click "Load Temporary Add-on", then select manifest.json from the dist/firefox/ folder. For permanent installation, install from Firefox Add-ons (AMO) when available.

Building from Source

The build script generates browser-specific builds from the shared source in src/:

./build.sh

This creates:

• dist/chrome/: Chrome build with Side Panel API manifest
• dist/firefox/: Firefox build with sidebar_action manifest

The JavaScript is identical across both builds. Only the manifest.json differs.

Requested Permissions

Sidebrief requests a few permissions in the manifest.json file.

activeTab allows the extension to read the URL of the current tab when you trigger a summarization via toolbar click or keyboard shortcut.

tabs allows the extension to read tab URLs from the sidebar context, where activeTab alone is insufficient.

contextMenus allows the extension to add "Summarize" and "Key Moments" to the right-click menu.

storage allows the extension to save your preferences (engine, language, API token) and recent summary history using the browser's built-in extension storage.

sidePanel (Chrome only) allows the extension to open and manage the sidebar panel.

kagi.com (host permission) allows the extension to send summarization requests to the Kagi API.

Privacy

Sidebrief runs entirely in your browser. There are no background servers, no hidden calls, and no analytics. The only time any data leaves your device is when you explicitly request a summary, at which point the page URL (or pasted text) is sent to the Kagi Summarizer API to generate it. Your preferences (engine, language, theme, etc.) are stored using your browser's built-in extension storage, which may sync across devices if you have browser sync enabled. Tiny Extensions does not collect or track anything. No analytics. No telemetry. No user data. When you request a summary, your interaction is governed solely by the Kagi Privacy Policy and Kagi LLM Policy.

License

Copyright (C) 2026 Seth Cottle

Sidebrief for Kagi Summarizer is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or any later version.

Sidebrief for Kagi Summarizer is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. Please see the GNU General Public License for more details.

Sidebrief bundles the OpenDyslexic font by Abbie Gonzalez, licensed under the SIL Open Font License 1.1.

Inspired by the official Kagi Summarizer Extension for Chrome & the built in summarizer in Orion. Love Kagi? Check out OpenKagi to share and discover community-made Lenses and Themes.

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Built by Seth Cottle. Part of Tiny Extensions. This is an unofficial extension and is not affiliated with, endorsed by, or connected to Kagi, Inc.