MiFis or MiFi dongles are compact, wireless devices, usually a little smaller than a smartphone, that create a localised Wi-Fi signal that you can use on the go. What is MiFi? MiFi devices are small, wireless devices that let multiple users and mobile devices share a mobile broadband internet connection. Some mifi hotspots are also plug and play devices, also known as Wi-Fi dongles. It's different to a mobile dongle, which only allows you to connect a single device, and to Wi-Fi, which is simply the name for the wireless. They amplify mobile signals that a MiFi device or hotspot can emit.