Is it permissible for a web developer to complete work on a website that includes both halal and haram restaurants, knowing that the website facilitates finding halal restaurants, and is it permissible to give charity from his salary if there is doubt in it?

It is forbidden to add advertisements for prohibited foods and drinks, such as pork and alcoholic beverages, or for restaurants that serve them, because this constitutes direct assistance in sin. However, designing a general website for restaurants where the website owner adds restaurants is not forbidden, because there is no direct or intended assistance in what is prohibited therein.