GitHub UI Translator

English | 日本語

GitHub UI Translator is a browser extension (Chrome and Firefox) that translates GitHub's English UI into Japanese or Simplified Chinese using a local dictionary. It does not rely on external translation APIs or cloud services; all translation runs locally in the browser.

Features

• Performs all translation locally without sending page content or settings to external services
• Translates fixed GitHub UI text such as navigation items and buttons while avoiding user-created content areas such as READMEs, issues, comments, and code blocks
• Lets you turn translation on or off from the extension popup
• Translates the global header after GitHub's React hydration completes to reduce the risk of interfering with the global search; this can be turned off from the popup

Documentation

• Translation scope (Japanese)

Limitations

• Japanese and Simplified Chinese are currently supported. Additional languages are planned as coverage expands.
• Dynamic text containing numbers or dates, such as "3 commits" or "opened 2 days ago", is not translated. User-created content such as user names is also excluded. See Translation scope for details.
• Only github.com is supported. GitHub Enterprise and other custom domains are not supported.
• Tested on Chrome and Firefox. Other Chromium-based browsers (Edge, Brave, etc.) should also work but have not been explicitly tested.

Installation

Chrome

Install GitHub UI Translator from the Chrome Web Store.

If the Chrome Web Store is unavailable in your environment, such as on a company-managed device:

1. Download the .zip file from the latest release and extract it.
2. Open chrome://extensions in Chrome and turn on Developer mode.
3. Click "Load unpacked" and select the extracted folder.

Extensions installed manually do not update automatically. Repeat these steps when a new version is released. Your organization may also block Developer mode or manually installed extensions; in that case, contact your administrator.

Firefox

Firefox 142 or later is required.

1. Open the latest release page in Firefox and click the attached .xpi file.
2. When the installation confirmation dialog appears, click "Add".

If the dialog does not appear, drag and drop the downloaded .xpi file onto the about:addons page. The file is signed, so the extension stays installed across Firefox restarts.

Version 0.1.2 and later of the extension check updates.json in this repository and install newer signed XPI releases automatically. If you installed version 0.1.1 or earlier, manually install v0.1.2 once to enable future automatic updates.

After installation, open a GitHub page such as https://github.com/... and supported UI text will be translated automatically.

Development install (load from the repository)

To customize the dictionary or contribute, clone the repository and load it directly.

git clone https://github.com/nobuo-miura/github-ui-translator.git

• Chrome: open chrome://extensions, turn on Developer mode, click "Load unpacked", and select the cloned folder (the one that contains manifest.json).
• Firefox: open about:debugging#/runtime/this-firefox, click "Load Temporary Add-on…", and select manifest.json inside the repository. A temporary add-on is removed when Firefox restarts, so it needs to be reloaded each session.

Usage

• Click the extension icon in the toolbar to open the on/off toggle and the language selector. Japanese and Simplified Chinese are bundled today; the dropdown is ready for additional languages once more dictionaries are added.
• Changing the toggle or the language reloads open GitHub tabs so the new setting takes effect.
• The popup also lets you select whether to translate the global header and has a link to this repository. Changing this option reloads open GitHub tabs. Global header translation is on by default and waits for GitHub's React hydration to finish before translating; turn it off if the global search ever fails to open.
• Open the extension options page (chrome://extensions on Chrome, about:addons on Firefox) to view the bundled dictionary information and extension version.

Customizing the Dictionary

You can add or change translations by editing the dictionary file for the language you want to change directly (e.g. dictionaries/ja.json, dictionaries/zh-CN.json). Entries are grouped into sections by GitHub screen (repository navigation, repository Settings, organization Settings, etc.), each preceded by a // ==== comment line, so you can tell at a glance which screen an entry belongs to and quickly spot when GitHub's UI text changes.

{
  "language": "ja",
  "name": "日本語",
  "translations": {
    // ==== Repository navigation ====
    "Code": "コード",
    "Issues": "イシュー"
  }
}

• The file is JSON with // line comments (JSONC-style). Only whole-line comments are supported — trailing comments after a value on the same line are not. The extension strips comment lines before parsing, since standard JSON.parse/fetch().json() do not support comments.
• Dictionary keys must match the original English text exactly. Leading and trailing whitespace is ignored for both visible text and supported attribute values. For visible text only, consecutive whitespace—including line breaks—is collapsed to a single space. Attribute values such as aria-label, placeholder, button value, and data-disable-with retain their internal whitespace when matched. Dictionary keys themselves must not contain leading or trailing whitespace.
• After editing the dictionary, reload the extension (chrome://extensions on Chrome, about:debugging on Firefox).

Adding a new language

1. Add dictionaries/<code>.json (e.g. dictionaries/en.json) in the same format.
2. Add { "code": "<code>", "name": "<display name>" } to languages.json. The popup and options page both load this shared list.
3. Run node scripts/validate.mjs to check the dictionary format, duplicate keys, metadata, and key parity with the other bundled dictionaries.

The popup, options page, and extension metadata use the browser extension _locales mechanism independently of the GitHub translation dictionaries. To add a new language for the extension's own UI, also add _locales/<code>/messages.json with the same message keys as _locales/en/messages.json.

Project Structure

github-ui-translator/
├─ manifest.json
├─ shared.js        # Shared language list and extension UI localization helpers
├─ languages.json   # Bundled GitHub translation languages
├─ content.js       # Translation engine that scans the DOM using an allowlist
├─ popup.html/js    # Toolbar popup with the translation toggle
├─ options.html/js  # Dictionary information and version display
├─ updates.json     # Update manifest for the self-distributed Firefox extension
├─ _locales/        # Localized popup, options, and extension metadata messages
├─ dictionaries/
│  ├─ ja.json       # Japanese dictionary
│  └─ zh-CN.json    # Simplified Chinese dictionary
├─ docs/
│  ├─ translation-scope.md     # English version
│  └─ translation-scope.ja.md  # Japanese version
├─ scripts/
│  └─ validate.mjs  # Dictionary and localization validation
└─ icons/

License

MIT License