Apple’s iPhone X supports fast-charging via its wired Lightning connector and 7.5W wireless charging through a Qi-compatible pad or dock. (Many new cars also come with a Qi-based wireless charging pad option, which will work with the iPhone 8 and iPhone X models.)
Apple stores sell both Belkin and Mophie brand wireless charging pads, which it claims represents “the best implementation of the Qi standard.” But those models are also pricey (as much as $60) and you can use any pad or dock that conforms to the Qi-wireless charging specification.
“Fast charging” is basically anything greater than a standard 5W of power transfer. While it remains to be seen what Apple’s upcoming AirPower charging pad will enable in terms of fast charging – 7.5W or 15W (the Qi specification supports both) – currently “fast charging” an iPhone X using 7.5W will bring it to 50% after a half hour. (Fast charging is expected to arrive with iOS 11.2.)
Two things to look for in a wireless charger are an LED light to indicate when the phone is properly aligned to receive a charge and foreign object detection, which ensures foreign metal objects will not heat up if they come in contact with the charging pad or dock.