Until now, the CalJ app calculated the entrance time of Shabbat at 18 minutes before sunset, which is the most widely held opinion in the world. Yet some cities observe a tradition of advancing Shabbat by a few more minutes, and this tradition holds the strength of Halacha, according to some, although it is extremely difficult to establish the sources.
For example, in Jerusalem, the candles are lit 40 minutes before the Shekiya, in Haifa 30 minutes.
I had been proposing for some time a specific option in CalJ for Jerusalem, and its 40 minutes. Now in version 2.37 of the Android edition, I have generalized the function, and you can specify a particular advanced Candle rule in each of your bookmarked cities.
The feature will be available soon in the iOS edition, אי’ה.
CalJ automatically tries to configure the exception time for the cities I know. For any other place you have to do the setting manually. If you know particular cities that have a lighting time other than 18 minutes, please do not hesitate to let me know!