Does anyone know of any NFC app that allow me to program an NFC tag to toggle data on and off? None of the apps that I have tried will do this.
Mobile data network status is controlled by different settings on different types of devices. For instance, toggling mobile data on and off on a WiMax device uses a different setting than toggling mobile data on an LTE device. This is the case, at least, with some devices. It's long been an issue for application developers who want to have a "universal" mobile data networks toggle programmatically (i.e. via code). In the past, developers used the MODIFY_PHONE_STATE permission for most methods of enabling/disabling mobile data, but that permission was marked as "system use only" in 2.3.
Here's an example showcasing the differences and difficulties.
Because of this, it may not be quite so easy to find one that has the option. I'm not saying there
isn't one, though. I haven't looked at the offerings enough to give you a concrete answer.