Gallery: External storage for your iPhone

Amid all the rumours surrounding Apple's 2017 iPhones, no-one suggested that the company might include a MicroSD card slot that would allow you to expand the iPhone's internal storage. The iPhone 8, 8 Plus and X all start at 64GB, while earlier models offer just 32GB at the entry level.

Apple's own storage upgrades are expensive, of course -- but there are other options that can help you to free up some space on your iPhone, as well as providing useful backup features in case of accidents. There are plug-in memory sticks that you can carry around in your pocket, wi-fi hard drives that can be shared across Macs and PCs, and even NAS drives that can sit at home or in your office and provide remote backup options when you're travelling.

Here's a selection.

The Link has been around since 2015, and if you shop around you can find it on sale for as little as £12.99 ($12), which makes it one of the most affordable storage options currently available for the iPhone.

In fact, the Link is primarily designed as a pocket-size Lightning-connected battery charger, with a 3000mAh battery to top up your iPhone when you're out and about. However, it also includes 16GB of on-board storage so that you can quickly backup a few photos or videos and free up some space on your iPhone. The Link app has a few rough edges, but it'll do the trick for simply transferring files when you're on the road.

£12.99 ($12)

MobileFun

Kingston's Mobilite started life as a wireless adapter that allowed you to connect an iPhone or other mobile device to a standard USB hard drive or memory stick via wi-fi. However, this latest Pro model has turned into something of a swiss-army-knife for travellers. You can plug in a USB storage device or insert an SD memory card and then use the Mobilite app to transfer files via the Mobilite's built-in wi-fi -- speedy dual-band 802.11ac, no less. Alternatively, the Mobilite Pro also includes 64GB of its own internal storage, and even a 5,400mAh battery for charging the iPhone on the move.

£95 ($100)

Kingston

The Fuel is very much designed for outdoor use, with a sturdy, rugged design that will help to keep your files safe when you're hiking around the countryside, or shoving your bags into a luggage compartment on a plane.

The Fuel can be used as a straightforward portable hard drive, with a USB 3.0 interface for connecting to a Mac or PC, and either 1TB or 2TB of storage capacity. However, the Fuel also includes 802.11n wi-fi, allowing you to use the Fuel app to transfer files from iOS or Android devices. The app also supports Apple's AirPlay, which lets you stream all your holiday photos and videos to an AppleTV when you get home.

£135 ($150) for 1TB
£175 ($185) for 2TB

Lacie

Leef's iBridge is perhaps the best-known storage add-on for the iPhone, thanks to its simple, practical design.

The iBridge is really just a straightforward flash memory stick, available with 32GB up to 256GB of storage capacity, and it has a USB 3.0 connector so that it can quickly be plugged into a Mac or PC. However, it also has a Lightning connector for iOS devices, and the Leef app provides quick and easy options for backing up and transferring files when you need to free up some space on your iPhone or iPad. It's neatly designed too, with a little rubber case that can hook onto a key ring and travel around in your pocket.

from £79.99 ($70) for 32GB

Leef

SanDisk's iXpand range includes a number of useful storage devices and accessories for the iPhone, and the latest addition to the range is the new iXpand Base.

As the name suggests, the iXpand Base acts as a little charging dock for the iPhone. The Base isn't portable -- it doesn't have its own internal battery, so you'll need to connect it to mains power when you charge your iPhone. However, it includes 32GB- 256GB of internal storage, and the iXpand app can be used to automatically backup photos, videos and contact info as soon as you connect it to the Base, so it's a handy back-up option that you can use at home or in the office without turning on a computer.

from £53.99 ($50) for 32GB

SanDisk

The iXpand Flash Drive is a very straightforward, portable option for adding some extra storage to your iPhone. As the name suggests, it's really just a conventional Flash memory stick, and is available with 16GB up to 256GB of storage. However, it has both USB 3.0 and Lightning connectors, so you can use it with Macs and PCs as well the iPhone and iPad.

The iXpand app can be used to automatically backup photos and videos as soon as you plug it into your iPhone. The app also allows you to stream and view a variety of video file formats that are stored on the Flash Drive, so you could top it up with a few episodes of Game Of Thrones to watch on a long journey without using all your iPhone storage.

from £29 ($40) for 16GB

SanDisk

The software side of Seagate's Personal Cloud is a bit untidy, with a number of different apps providing different features. However, the Personal Cloud is still a versatile NAS drive and media server that provides a central storage device for multiple Macs, PCs and mobile devices.

The drive is available with 3TB- 5TB of storage, and there's a dual-drive version available that provides RAID mirroring for extra protection. As well as providing shared storage for your home network, the drive also allows you to create a 'personal cloud' account that provides remote access, and the Seagate Media app provides file transfer and back-up features for iOS and Android devices.

from £130 ($170) for 3TB

Seagate

Seagate's Wireless Plus drive has been around for a couple of years, and you can now pick it up fairly cheaply, at around £100 for the 1TB model or £140 for 2TB.

The Wireless Plus works as a conventional portable hard drive, measuring just 21mm thick and weighing 272g, so it's easy to carry in a backpack or briefcase when you're travelling. There's a standard USB 3.0 interface for connecting to a PC or Mac, but the Wireless Plus can also connect to multiple mobile devices via wi-fi and use the Seagate Media app to back-up or stream files when you need to save space on your iPhone (the app also works on Android and Amazon Kindle). internal battery provides about 10 hours of battery life when transferring or streaming files via wi-fi.

from £100 ($140) for 1TB

Seagate

Silicon Power isn't a well-known name here in the UK, but its Z50 flash drive is a sturdy and affordable option for quickly adding some extra storage to your iPhone.

The compact little memory stick measures just 42mm long, 14.5mm wide and 6.6mm thick, so it's easy to slip into your pocket when you're travelling. The metallic case is solid enough to cope with life on the road, and the dual Lightning and USB 3.1 interfaces allow you to use the Z50 with both iOS devices and conventional Macs and PCs. The Silicon Power app isn't the most elegant we've come across, but it provides basic file transfer features along with data encryption to keep your files secure.

from £60 ($45) for 64GB

Silicon Power

Western Digital recently updated its My Cloud range of NAS drives with the new My Cloud Home, which provides 2TB-6TB of shared storage for home users. The company does a good job of making NAS drives easy to use for less experienced people, and provides a versatile mobile app that allows iOS and Android devices to upload photos, videos and other files over the internet.

Along with the My Cloud Home, there's also a new dual-drive model called the Home Duo that includes a RAID mirroring option for extra data protection. And, as always, the company continues to provide the My Cloud Expert and Pro models, which provide more advanced features for larger organisations.

from £125 ($160) for 2TB

Western Digital