Must one make up for the days one broke one's fast based on the timing of the "Salaty" electronic program, which differs from the timing on the Islamic Society of North America (ISNA) website?

A fasting person does not break their fast except with certainty or dominant conjecture about sunset. If you broke your fast relying on a calendar prepared by people of experience and trustworthiness, then there is no blame on you and no need for a makeup fast (qada'), for the disagreement of others does not mean it is wrong. However, if you broke your fast doubting the sunset, and then it became clear that it had not occurred, then you must make up that day. And if you broke your fast based on dominant conjecture, and then the contrary became apparent, scholars have differed regarding the obligation of a makeup fast; it is preferable to make it up as a precaution and to avoid scholarly disagreement.