I work with a number of clients who sell products over the Internet. Is it permissible to run ads on Shabbat that direct potential buyers to a website that is owned by Jews on Shabbat (the ads were set in motion before Shabbat)? Does it make a difference of the majority of the buyers are non-Jews? In addition to ads, is it permissible to have a website that accepts orders on Shabbat even if the owner of the website does not actively do anything with the orders until after Shabbat is over?
This topic and similar issues were discussed at length by nowadays Poskim, here are the conclusions based on an article I wrote on the topic: 1. One who would like to honor Shabbat and go according to all opinions, will close the website on Shabbat in accordance with the times in his country, and also will install the computer program which closes the site in each country according to its local times. 2. One who is lenient and leaves the website open on Shabbat has who to rely on whether the users of the website are gentiles or Jews. Nevertheless if it is highly probable that Jews who violate Shabbat will be surfing, it is definitely the proper and right thing to do, to shut down the website. 3. There is another possibility - to rent out the website to a gentile for weekends, where the profits will go to the gentile who will pay rent to the Jew out of his profits. 4. Regarding this issue of being open on Shabbat there is no difference between keeping a commercial website open, or keeping running advertisements that refer visitors to the site. 5. It is recommended for one who keeps his website open on Shabbat, to note in the conditions of the site that the deal does not apply on Shabbat, but only in the beginning of the next business day, in order to avoid the possibility of transgressing the rabbinic prohibition of Mekach Umemkar (doing business) on Shabbat according to all opinions. 6. In a case of a site that does not sell products but provides information for a fee, there is another reason why it is proper to be stringent and not keep it open on Shabbat. It may be considered Sechar Shabbat (the rabbinic prohibition of getting paid for work or services which were provided on Shabbat). But if it is a long term subscription then there is no prohibition of Sechar Shabbat because he is charging a global fee, not specifically for Shabbat. 7. If it is known that the website belongs to an observant Jew, that is another reason why it is proper to close the site on Shabbat. Nevertheless if one is lenient and keeps his site open, it is recommended he should indicate in a prominent place on his site that all transactions do not apply on Shabbat but in the beginning of the next business day, in order to avoid the possibility of causing Chillul Hashem (desecration of the Divine Name, act of blasphemy) of people saying that he does business on Shabbat. [למקורות בהרחבה ראה מאמרי "אתרי אינטרנט מסחריים בשבת"].