Time4J

Supports over 20 calendars including Chinese, Hebrew, and Persian, as listed in the README, enabling accurate historical and international date handling beyond standard Gregorian.

Provides precise UTC leap second support and astronomy calculations like sun/moon positions, essential for scientific applications where time scale accuracy is critical.

Emphasizes compile-time safety and requires explicit locale/timezone specifications, preventing errors like adding clock units to dates, as highlighted in the design remarks.

Offers high-performance parsing and formatting with extensive customization options, outperforming Joda-Time and JSR-310 in parsing speed according to the README.

Includes built-in resources for 95 languages with localized duration formatting, filling gaps left by platform resources, as stated in the internationalization section.