Hebrew Date KDE Widget: dual calendar display for Plasma 6

Living in Israel means constantly needing to know both the Gregorian and Hebrew dates, and it's not just a nice-to-have — the Hebrew calendar drives holidays, religious observances, and a surprising amount of everyday life here. School schedules, government offices, and social events all reference Hebrew dates, and the day boundary falls at sunset rather than midnight, which adds another layer of complexity that most calendar software simply ignores. KDE Plasma didn't have a widget that showed both calendars cleanly in the system tray, so I built one.

Configurable dual-calendar display

The widget sits in your system tray or on your desktop and displays both Gregorian and Hebrew dates. You can configure which date appears first, choose between three Hebrew date formats (transliterated with slashes, simple transliteration, or full Hebrew characters with gershayim — the typographic marks used in Hebrew to denote abbreviations and numerals), and toggle year display for either calendar. The display adapts to context: larger fonts when placed on the desktop as a standalone widget, smaller when embedded in a panel. You can override the auto-sizing and set your own font sizes for each context, which matters when you're trying to fit dual-calendar information into a panel that was designed for a single clock.

The sunset problem

Here's the engineering challenge that makes this more interesting than a simple date widget: the Hebrew day changes at sunset, not midnight. Friday evening after sunset is already Shabbat — Saturday in Hebrew calendar terms — even though the Gregorian calendar still says Friday. Getting this right requires knowing the exact sunset time for the user's location, which varies by latitude, longitude, and time of year. The widget handles this by querying the Hebcal API with your configured coordinates to determine the precise sunset time, then scheduling updates strategically: once at midnight for the Gregorian date transition, and 30 seconds after sunset for the Hebrew date transition. This means only two or three API calls per day instead of constant polling, and sunset times are cached in persistent storage so if the API is temporarily unavailable, the widget falls back to the last known date rather than showing an error.

Installation is a single command using kpackagetool6, or you can use the included install script. After adding the widget, configure your location coordinates in the settings so the sunset calculations are accurate. I've been running it daily on Ubuntu 25.10 with KDE Plasma 6 on Wayland without issues. If you're a KDE user who needs Hebrew calendar awareness on your desktop, the project is on GitHub.