What is the ruling on working on a fitness application that contains pictures of women with bare arms and hair, and asks for gender identification between "male, female, or other"?

If the work of the questioner in this application requires him to place an image of a unveiled woman, or to add a special field for those who are neither male nor female (homosexuals), then it is not permissible for him to program this application. However, if the application provides spaces for images or fields for selecting gender, and this data is filled in by the project owner himself, so that the questioner does not directly engage in anything forbidden with his own hands, then it is permissible for him to do so; because the questioner is responsible for his own actions, not for the actions of the project owners. The Almighty said: "Every person is a pledge for what he has earned" (Al-Tur: 21), and He, glorified be He, said: "Every soul, for what it earned, is Rahn (held responsible)" (Al-Muddathir: 38).