Hebcal (pronounced HEEB-kal, as in Hebrew calendar) is a perpetual Jewish calendar program. It includes tools to help you generate a list of Jewish holidays for any year (past, present or future). Also available are a Hebrew date converter, Shabbat candle lighting times and Torah readings. Create a personal list of Yahrzeit (memorial) dates.
Hebcal is available in Go, JavaScript, Swift, C, Java and Perl.
The key routines are translations of Dershowitz & Reingold's lisp code in GNU-Emacs 18.
Hebcal is made available for free under the GNU Public License. However, I would like to hear from you. If you like hebcal, send me a message! If you don't like hebcal, well, let me know also, but be gentle.