Is working for an information technology company that facilitates access to diverse content, such as the Quran and songs, and receiving a salary for it, considered unlawful (haram)?

The basic principle is the impermissibility of aiding in sin. It is not permissible for a Muslim to work in anything that involves assisting in sin and aggression, due to the Almighty's saying: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression." Therefore, it is not permissible to work in programming that is used to aid in what is unlawful, and one must seek work free from these prohibitions.