Is it permissible for me, as a programmer, to create a website for a company that sells natural products, including alcoholic beverages, and would my earnings from this work be unlawful (haram)?

If the products predominantly sold on the halal website, you are permitted to establish it, as long as your work does not involve introducing prohibited products. However, if the products predominantly sold are haram, then it is not permissible to establish it, as it involves cooperation in sin. Sheikh Ibn Uthaymeen mentioned that if the predominant activity of a company is haram, then it is not permissible to work for it. If the predominant activity is permissible, then it is permissible [to work for it]. And if they are equal, one should not do it, prioritizing the side of prohibition.