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The tool has come under fire for inadvertently and automatically taking up people’s data allowance, but other apps are probably doing far more damage

OS 9 Wi-Fi Assist, which lets your phone switch to your data connection when it's quicker, has come under blame for eating up people's data without them knowing about it. And while it might be true that the feature is using more data than you realised, there’s probably plenty of other things sat on your phone eating up your allowance.

The Wi-Fi Assist is built for use when the normal wireless connection is slow, and pushes people onto their phone’s network instead. But many have worried that since it can swap between a Wi-Fi connection and a network data connection seamlessly, and it’s on by default, people might be using their data connection when they thought they were on Wi-Fi.

(If you're worried about the feature, or want to check if it's turned on, you can find out how to do so here.)

However, a huge range of apps are likely using more data without users knowing it. The best way to check what’s taking up all of your allowance is to head to the Settings app, and click Mobile Data or Cellular.

That will give you a full list of all of the apps on your phone, with the amount of data each of them has used written underneath. You can use the slider to the side to turn their data connection on or off entirely — but that might be a little extreme.

More useful might be either manually limiting your use of those apps while on a data connection or turning off background app refresh. That feature allows apps to load up information while you’re not using them — so that it’s ready when you open it back up — but also mean that it might be pulling down information that you don’t need.

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To do that, you can head to the individual app’s settings and choose either to turn off cellular data or to turn off just background app refresh.