Most external hard drives are connected directly to you computer (or to a port on your router in the case of an NAS). Wireless external hard drives use Wi-Fi and can be accessed from a computer, smartphone or tablet. Because these drives don't rely on a physical connection, they're more convenient to use with laptops and tablets than a wired external drive, which keeps you tethered to a desk or table. They're also small enough to carry with you on the go, though not quite as compact as most portable hard drives.
By far the most recommended wireless hard drive is the Seagate Wireless Plus (Est. $180). This drive provides a terabyte of storage space that you can access wirelessly from up to eight devices at once. This drive comes preformatted in the Microsoft NTFS format and will not work in any other format, but it includes software drivers that allow it to work with a Mac. Free apps are also available for use with both iOS and Android devices. If you want a physical connection, the Wireless Plus includes a USB 3.0 port.
The Seagate Wireless Plus is one of the top-rated hard drives at Macworld, and it also earns Editors' Choice nods at PCMag.com and Laptop magazine. Reviewers like its versatility, large capacity and long battery life (up to 10 hours). However, they say its transfer speeds aren't terribly fast, and they disagree about the usefulness of its media app. While most reviews describe it as simple and intuitive, CNET notes that it "doesn't natively support all popular digital video formats," and StorageReview.com says it has some "quirks" when it comes to usability. Reviewers at Amazon.com seem to agree. While they like the drive's functionality, we saw many complaints that it's not intuitive to use -- and Seagate doesn't provide a manual to explain any of its functions. Some users also complain that the Wi-Fi connection can be glitchy and unstable.
A couple of other wireless drives earn some positive feedback, but reviews are not as uniformly positive as those for the Seagate Wireless Plus. For example, the Corsair Voyager Air (Est. $180 for 1 TB) is recommended as one of the best available external hard drives at CNET and also earns a recommendation from StorageReview.com. Editors there are particularly impressed that it includes a gigabit Ethernet port, which allows it to function as a true NAS. However, when hooked up to the Internet through the cable, it can't pass the Internet access through to other devices wirelessly. Reviewers also say that its battery life is shorter than the Seagate's, maxing out at seven hours, and its mobile app is a bit clunky.
The LaCie Fuel (Est. $200 for 1 TB) is an Editors' Choice at PCMag.com and is also recommended at StorageReview.com. Reviewers like its large capacity and long battery life, and they note that it uses the same well-designed media app that comes with the Seagate Wireless Plus. Testers at StorageReview.com found the Fuel significantly faster at transferring files than its competitors, including the Wireless Plus. However, tests at CNET found virtually no difference between the two, and the editors say there's no good reason to choose the Fuel over the Wireless Plus.