Is my fiancée’s use of the "Vigo" app for chatting and hosting chanters, reciters, and singers—by voice only—and the salary she receives from it, permissible (halal) or forbidden (haram)? And is the commission she gets for bringing in subscribers who offer various content permissible (halal) or forbidden (haram)?

The ruling on working in chat and earning from it depends on the nature of the communication: if it involves a soft speech (khudu' bil-qawl), then it is forbidden, and the earnings from it are ill-gotten (khabith). However, if it is speech that is regulated by Islamic law, such as chanting or recitation, then it is permissible. It is difficult to control this matter, as it often involves softening the voice and making speech alluring to attract customers, which often serves as a trap for those in whose hearts is a disease. Allah Almighty says: "Then do not be soft in speech [to men], lest he in whose heart is a disease should covet, but speak with appropriate speech." There are many avenues for lawful earnings, and whoever gives up something for the sake of Allah, Allah will compensate him with something better.