hebrewcalendar.net was first brought up in 1999 and ran for about 20 years. Over time I had little opportunity to maintain it, and in the meanwhile other sites such as zmanim.org and chabad.org had been developed. In 2026, with the help of Claude AI, managing the visual web part became much easier, so I restarted it.
We generally follow Chabad zmanim standards.
The one addition is Tzait Hakochavim per Rabbeinu Tam (72 minutes after sunset), which is not part of the standard Chabad set but is included for those who observe it.
The halachic calculation library powering this site is written in Java and is open source on GitHub. A companion C library for the Hebrew calendar arithmetic is also available on GitHub.
Sun times are computed without elevation adjustment, which is the standard approach for halachic purposes. The underlying API does accept an elevation value for those who know what they are doing.
Location search and geocoding use the Google Places API.
Questions or feedback? Email support@hebrewcalendar.net.
© Isaac Mushinsky, 1998–2026