Is a medical student sinful for working on programming and developing a computer program for beauty salons and men's and women's barbershops, which do not observe Sharia controls, knowing that he does not participate in selling cosmetic products, and that he is in dire need of this work to cover his study and living expenses?

Allah commanded cooperation in righteousness and piety and forbade cooperation in sin and aggression, just as the Messenger of Allah, peace and blessings be upon him, commanded changing evil. Designing programs and websites for a company primarily involved in haraam (unlawful) activities is not permissible, even if you do not directly engage in the haraam yourself, because it is considered aiding in it. Everything that is used in haraam or is predominantly thought to be so, its manufacturing, sale, and promotion are forbidden. You must search for a permissible job free from sin, and whoever abandons something for the sake of Allah, Allah will compensate him with something better.