Assalamualaikum, I made the software which is the addin for iTunes. My app is to help find and delete duplicate items inside iTunes. Well, it can find anything from video, podcast, audio, lecture audio, etc but as iTunes is mainly a music player people mainly used my app to find duplicate songs. My copywriting on my website also stated word "music" & "song". My question is the earning from this app halal or haram? If it is haram what should I do with the money I get so far? At the time I made the app I don't know that the music is haram, sometimes later I know it and then asked local ulama but they say music is halal. Thanks in advance.

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His Slave and Messenger.

You have mentioned in your question that iTunes is mainly a music player and that people mainly used your app to find duplicate songs and the like. In fact, listening to songs the way they are nowadays is prohibited because it involves listening to musical instruments, immoral lyrics and foul and obscene language. Verily, watching the video clips is an even graver sin, given the impermissible exposure of women’s bodies and adornment that they mostly contain. Therefore, it is impermissible to add your new app to iTunes because it involves helping others to commit sins and misdeeds. Allaah, The Exalted, says (what means): {... do not cooperate in sin and aggression...} [Quran 5:2]

For more benefit, please refer to Fatwa 85287.

The money earned through that app is not good; you should dispose of it by spending it on public services benefitting the Muslim community or spending it in charity for the poor and needy. Your excuse that you were unaware of the impermissibility of music when you created this app does not allow you to continue earning money through it after knowing about its impermissibility. However, you may develop the app to be especially used in what is lawful or what is most likely allowable.

As for the money earned through the app before knowing the impermissibility of music, following the Fatwa of the scholars who informed you that music is lawful, you are entitled to use this money and there is no harm in that. The same applies to the money that you had spent before repenting from this sin. But it is forbidden for you to earn any money through it after you have learned that it is impermissible. Please refer to Fatwa 88714.

We would like to draw your attention to the fact that singing is of different kinds, and each has its religious ruling in the Sharee'ah:

First: If the singing involves a musical instrument, then it is forbidden to listen to it whether from a man or a woman. Ibn Hajar Al-Haytami wrote, “The grave sins no. 446, 447, 448, 449, 450, and 451 are: playing stringed instruments, listening to them, playing flute, listening to it, playing Koobah (drum) and listening to it ...”  [Az-Zawaajir ‘An Iqtiraaf Al-Kabaa'ir]

Second: If the singing is not accompanied by a musical instrument, it is of two kinds:

1. Singing of women for men. This is absolutely impermissible.

2. Singing of a man. In this case, the songs should be examined. If he is singing appropriate lyrics about permissible subjects, promoting goodness and lawful matters, then many jurists have deemed it allowable. If it contains inappropriate subjects like promoting evil and immorality, or describing a woman's body or alcohol or the like, then, it is prohibited.

Allaah Knows best.