How to stop your Android phone secretly collecting personal data

Even when the screen is off, many Android apps are up to no good

Summary created by Smart Answers AI

In summary:

• Tech Advisor explains how Android apps secretly collect personal data through invisible trackers that build detailed user profiles for advertising, even when apps aren’t actively open.
• This matters because common apps like games and torch apps gather location history, device information, and usage patterns without explicit user awareness, impacting privacy and battery life.
• Key solutions include restricting app permissions for location/camera/microphone access, deleting advertising IDs, using anti-tracking apps like DuckDuckGo, and employing ad-blocking DNS services. Detailed instructions are provided below.

Whether it’s in your trouser pocket, on your bedside table or seemingly unused on your desk, your Android smartphone never sleeps. Even when the screen is off, many apps are busily sending data back to their servers in the background – often taking personal data with them without you even realising it.

The obsession with data collection in the Android ecosystem is widespread and it applies to tablets too, not just phones. Often, it’s not even malicious hackers but perfectly ordinary apps such as torch apps, games or weather services that deeply invade your privacy. Consenting to an app has never been riskier or more problematic.

The good news is that you’re not defenceless against this. In this guide, we’ll show you which permissions you need to pay particular attention to, how to stop covert background access and how to systematically reduce tracking on your smartphone.

The invisible data vacuum cleaners: what apps really want to know

Many users assume that an app only collects data when it is currently open. The reality, however, is quite different: numerous apps are equipped with so-called invisible trackers (third-party modules).

These modules merrily collect information in the background to create detailed user profiles for the advertising industry. You may be familiar with this problem from your web browser.

Among the most commonly collected – and often unnoticed – data are:

• Location history: Where do you work, where do you sleep, where do you shop?
• Device information: Which mobile phone brand and model do you use and what is your battery level?
• Usage behaviour: Which other apps have you installed and when do you open them?

The most critical permissions – and how to restrict them

When you’re in a hurry, you sometimes blindly grant apps permissions during installation that they don’t actually need to perform their intended function. Why does a simple notes app need access to your location? Why would an offline game want to access your contacts?

Pay particular attention to these three sensitive areas:

1. Location (GPS)
Many apps track your location constantly. Not only does this drain your battery, but it can also easily create a comprehensive profile of your movements. The solution: Change the permission from ‘Always allow’ to ‘Access only whilst using the app’ or revoke the permission completely.

2. Microphone and camera
A nightmare for many users: is your mobile listening in? On Android, a small green dot in the top corner of the screen indicates when the microphone or camera is active. Nevertheless, only apps that genuinely need this access (such as messaging apps or the phone app) should be granted it.

3. Contacts and call logs
By granting access to your address book, you’re not only sharing your own details but also the phone numbers and addresses of all your friends and acquaintances with the app developer. Be particularly restrictive here.

How to stop data leakage on your smartphone

In just a few simple steps, you can significantly curb the flow of data on your smartphone. Take five minutes to carry out this systematic check.

Note: As menu structures vary depending on the smartphone manufacturer, if in doubt, you can simply use the search function at the top of the Settings menu to find terms such as ‘Permissions’ or ‘Battery usage’ straight away.

Step 1: Tidy up the permissions manager

Here you can see at a glance which apps are allowed to access what.

1. Open your smartphone’s settings.
2. Tap on Apps (or ‘App Management’) and then on Permissions (or ‘Permissions Manager’).
3. Go through categories such as Location, Camera or Microphone.
4. Tap on any apps that shouldn’t be there and select ‘Don’t allow’.

Step 2: Restrict background activity

Stop apps that are secretly running in the background and sending data. Here’s how:

1. Go to Apps in Settings, then tap‘App battery usage’.
2. Select a data-hungry app (e.g. Facebook or a free game).
3. Select the “Restricted” option or toggle off “Allow background use”.

Step 3: Stop ad tracking

For a long time, Android assigned a unique advertising ID to every device. On current devices (such as the latest Google Pixel models), this local feature – as well as the ‘Privacy Sandbox’, which was once planned as a replacement – has now been completely removed from the system settings.

Here’s how to stop tracking on every device instead:

1. Checking on older devices: Use the search bar in Settings to search for ‘Advertising ID’. Once you’ve found the option, tap ‘Delete Advertising ID’.
2. The global solution: As Google has now almost entirely shifted ad control online, a single tap on your smartphone is no longer enough. Open your browser and log in to your Google account (https://myaccount.google.com/). Go to Data & Privacy, scroll down to Personalised ads and switch off ‘My Ad Centre’ completely.
3. Isolate sensitive apps: On new devices, Google now relies on local security mechanisms rather than the sandbox. From Android 15 onwards, use the “Private Space” or “Confidential Profile” feature. This allows you to move particularly data-hungry apps into a separate, password-protected area, where they are isolated from the rest of the system and can no longer collect data in the background. This deprives advertising networks of the basis for creating a profile from your clicks and isolates prying apps at the system level.

Tech Bodyguard: Block trackers system-wide

If you want to take it a step further, you can almost completely disable tracking within the Android ecosystem. Instead of configuring each app individually, you can filter the data traffic of the entire smartphone.

• Use anti-tracking apps: Free tools such as the DuckDuckGo app (Download) offer a feature called ‘App Tracking Protection’. This actively blocks connections to known advertising and tracking networks in the background before the data leaves your device.
• Use ad-blocking DNS services: Apps such as Blokada (Download) or entering a private DNS server (such as AdGuard DNS) in your Android network settings act as a system-wide gatekeeper. They automatically intercept tracking requests from apps and browsers and ensure they come to nothing.

Bonus tip: Use data-efficient alternatives

Many popular apps are data-hungry. However, there are often open-source alternatives that do without trackers entirely. The alternative app store F-Droid offers exclusively free and privacy-friendly applications – from calendars and messengers to PDF readers.

Conclusion

Your Android phone doesn’t have to be a data leech. Often, a critical look at the permissions manager is enough to pull the plug on the worst data-suckers. If you consistently restrict permissions such as location and microphone access, limit background activities and delete your advertising ID, you’ll regain a large part of your privacy.

However, do proceed with a degree of tact when revoking permissions. Blocking permissions too rigorously can lead to malfunctions – for example, a messaging app without microphone access can no longer send voice messages, and a local weather app loses its usefulness without location access. By striking a careful balance, you can effectively protect your data without having to sacrifice the everyday convenience of your smartphone.