Your carrier will not charge you to use QuietSelf specifically. However, check your mobile plan to see how your data usage is billed. If you have unlimited data, then your carrier won’t charge you any extra fees to stream from QuietSelf. If you’re on a limited data plan, then time spent streaming from QuietSelf (or anywhere) will be part of your usage. If you are instead using WiFi to access QuietSelf, then your mobile carrier will not assess data usage fees. TIP: For QuietSelf, and everything else, always use WiFi when you can. It’s faster and doesn’t hit your data plan.