# Privacy Policy — YT Channel Volume

[日本語版はこちら (Japanese)](PRIVACY_POLICY_JA.md)

Last updated: 2026-10-30

## Overview

YT Channel Volume is a Chrome extension that balances volume per YouTube channel. It remembers a volume for each channel and, with loudness auto-apply on, adjusts each video and live stream to a target loudness from the loudness YouTube reports (Content Loudness data and the player's stats for nerds). This privacy policy explains what data the extension handles, how it is used, and where it is stored.

## Data Collected and Purpose

### Channel Volume Settings

- **What**: YouTube channel IDs, display names, channel URLs, the volume (gain) values you set for each kind (video / live), the loudness auto-apply switch for each kind, and the gain the extension works out for itself while that switch is on.
- **Purpose**: Used to automatically apply your preferred volume, or the gain auto-apply worked out, when you visit a video from a saved channel.
- **Storage**: Saved locally in `chrome.storage.local` on your device, and never transmitted to any external server. The gain you set is written when you set it. While auto-apply is on, the extension may also write the gain it calculates from a Content Loudness value or from a live stream's level, without an additional action from you.

### Extension Preferences

- **What**: Target LUFS level, display unit (% or dB), gain overlay toggle, and the loudness auto-apply default for each kind (video / live).
- **Purpose**: Customize the extension's behavior according to your preferences.
- **Storage**: Saved in `chrome.storage.sync`. When you have turned on Chrome sync, every computer where you are signed in to Chrome with the same Google account and have the extension installed uses the same preferences: Chrome carries them through your Google account, as it does for other extensions' synced settings. With Chrome sync off, they stay on your device. The extension itself sends them nowhere. Channel volume settings are not part of this and stay on each device.

### YouTube Video Metadata (read-only)

- **What**: Content Loudness (`loudnessDb`), `isLiveContent`, `isLive`, `channelId`, `videoId`, and the channel name from YouTube's player response; and the level of what is playing from the volume line of the player's stats for nerds (`cont.`, and on a live stream `live.`).
- **Purpose**: Display loudness information, calculate suggested volume, and work out the gain auto-apply plays. Determine whether content is a live stream or a regular video.
- **Storage**: `channelId` is the key a channel's settings are kept under, so it stays on your device once that channel is saved, and the channel name read beside it is saved as that channel's display name. The Content Loudness value, the level read from the stats for nerds, `isLiveContent`, `isLive` and `videoId` are held in memory only while the video page is open and are discarded on navigation. The gain worked out from the Content Loudness value or the live level, however, is saved with the channel's settings.

## Data NOT Collected

- The extension does **not** collect browsing history, analytics, or telemetry.
- The extension does **not** track which pages you visit on YouTube or any other site.
- The extension developer does **not** receive, store, or have access to any of your data.
- No data is sold, shared with third parties, or used for advertising.

## Where Data Is Sent

Nowhere. This extension makes **no external network requests**. Channel volume settings remain on your device. The extension preferences above are kept in Chrome's synced storage, which Chrome itself carries between the computers where you are signed in to Chrome with the same Google account, when you have turned on Chrome sync.

## Data Storage and Security

- Channel volume settings are stored in `chrome.storage.local`, and the extension preferences in `chrome.storage.sync`. Both are accessible only to this extension.
- Only the extension preferences are synced across devices, and only through Chrome sync. Channel volume settings, and anything read from YouTube, are never synced or stored in the cloud.
- Uninstalling the extension removes all locally stored data.

## Permissions

| Permission | Reason |
|---|---|
| **storage** | Save channel volume settings on your device, and user preferences in Chrome's synced storage |
| **activeTab** | Access the current YouTube tab to detect the channel, read Content Loudness, and apply volume adjustment |
| **host_permissions** (`youtube.com`) | Inject content scripts on YouTube pages to control audio volume via Web Audio API |

## Remote Code

This extension does **not** use remote code. All JavaScript is bundled locally within the extension package. The `page-bridge.js` content script runs in the page's main world (`"world": "MAIN"`) to read YouTube's player response data and the player's stats for nerds — this is local code, not remotely fetched.

## Single Purpose

This extension has a single purpose: **adjust and remember volume settings per YouTube channel**, bringing it to a target loudness from the loudness YouTube reports (Content Loudness metadata and the player's stats for nerds), using Web Audio API.

## Third-Party Dependencies

None. The extension contains no external libraries, SDKs, CDNs, or analytics tools.

## Changes to This Policy

Updates will be posted to this page with a revised date. Continued use of the extension after changes constitutes acceptance.

## Contact

If you have questions about this privacy policy, please open an [issue](https://github.com/semnil/yt-channel-volume/issues) on the GitHub repository.