週番号 作成者: RaphMo

Week Number displays the current week number directly in your Firefox toolbar with a clean, color-coded badge.

Features:
- Week number badge — See the current week number at a glance in your toolbar icon
- Week navigation — Browse past and future weeks with simple arrow buttons, and jump back to today with one click
- Date range display — View the full date range (start and end) for the selected week
- Customizable badge color — Pick your preferred color from a built-in swatch
- ISO or US weeks — Choose whether your week starts on Monday (ISO 8601) or Sunday (US format); the week number and date range update accordingly
- Persistent settings — Your color and week start preferences are saved and restored automatically
- Fully localized — Available in 12 languages: English, French, German, Spanish, Portuguese (Brazil), Russian, Chinese (Simplified), Japanese, Polish, Italian, Dutch, and Arabic

Lightweight, privacy-friendly, and no data collection. Just a simple, useful tool for anyone who works with week numbers for their planning.