Malware, adware, fake apps, scams – just some of the dangers your Android device might encounter every single time you install something new.
The answer is simple, at least in theory. Independent testing shows that the best antivirus apps do a great job of keeping you safe, regularly blocking 100% of their test threats.
The problem comes in deciding which app to use, because although there are hundreds out there, many are very inaccurate, and some may themselves be malicious.
AV Comparatives 2018 Android Security report gives an idea of the scope of this issue. The company tested more than 200 apps, and although many performed well, 79 either detected less than 30% of the same malware, or regularly raised false alarms with popular clean files. That suggests around 4 in ten of the antivirus products you'll find in the Play Store are so poor that AV Comparatives considered them unsafe or even deceptive.
It's important to choose your security apps with extreme care, then. To help out, this article will highlight five of the best and most reliable free Android antivirus apps, as assessed by our own experience and the results of assessments by AV Comparatives and AV Test.
- Also take a look at the best security apps and antivirus for Android
Avast Mobile Security is one of the most popular Android security solutions around with more than 100 million installs reported on Google Play, and an impressive app rating of 4.5.
Avast has always had a good accuracy record, but it's got even better since the company acquired AVG back in 2016 and the apps have been updated to include the best of both product ranges. As a result, both AV Test and AV Comparatives now regularly show Avast Mobile Security as detecting 100% of their test threats.
Avast Mobile Security has a solid set of features which more than covers the basics, with app and file scanning, a web shield to detect and block dangerous links, and wifi monitoring to check the security of a network as you connect.
Bonus security and optimisation tools include a call blocker, a vault to protect access to personal photos, junk file cleaning to free up storage space and a power save feature which tweaks system settings to extend your battery life.
The free app has ads, but you can upgrade to remove these and add premium extras like anti-theft, app locking and the ability to contact support directly from the app.
Avira may be best known for its free PC antivirus software, but the company also delivers the goods on Android, with Avira Antivirus Security 2018 delivering excellent malware-hunting performance for millions of users worldwide.
A comprehensive antivirus engine scans apps on installation, as well as their updates and your external storage units to look for threats. Independent testing shows Avira regularly detects 100% of malware samples.
Avira also claims its specialist anti-ransomware protection blocks millions of ransomware attacks every month.
An Identity Safeguard feature scans the web for signs that your email address has been leaked in a data breach, raising the alert if it spots any issues. That's a welcome extra which you won't normally see in other free antivirus apps.
Bonus features include anti-theft tools and some handy reports on the privacy risks of your installed apps, while a web management console enables tweaking settings remotely or managing multiple Avira-equipped devices from one place.
Put it all together and Avira Antivirus Security 2018 delivers capable all-round protection for a free app, although there are a couple of issues which might persuade you to upgrade. The free app doesn't block infected or phishing websites at the browser level, and updates aren't as frequent as with the commercial edition, leaving you fractionally more exposed to zero-day threats.
Bitdefender's antivirus engine is one of most accurate and reliable around, and regularly tops the detection rate lists from the independent testing labs.
For example, the company managed a second place in AV Comparatives July-November 2017 Real-World Protection tests, just behind Panda, yet outperforming big names like Kaspersky, Avira and Avast.
Normally you might expect to pay a price premium for this level of security, but Bitdefender Antivirus Free gives you no-strings free access to the same industrial-strength antivirus engine as its commercial cousins.
Bitdefender's Autopilot technology ensures the app is extremely easy to use, as most security decisions are handled automatically. New apps are scanned as they're downloaded, for instance, catching any threats before they can harm your device, while storage is scanned when your device starts to reveal anything else.
Detection is carried out in the cloud, a smart design decision which reduces CPU usage, avoids the need to download and store bulky antivirus definitions, and ensures the app will pick up the latest threats as soon as they appear.
Bitdefender Antivirus Free has some limits, unsurprisingly. In particular, it doesn't include Bitdefender Mobile Security's real-time scanning of web pages to detect and block phishing and other malicious sites. You can always install another app to handle browsing protection, though, and as a pure antivirus app Bitdefender Antivirus Free is hard to beat.
Symantec's Norton is probably best known for its Windows security software, but the brand also has some quality mobile apps, and Norton Security and Antivirus for Android does a great job of keeping you malware-free.
The heart of the app is based around Norton's Mobile Insight, a powerful service which has analysed millions of apps and adds thousands of new applications every day. Mobile Insight doesn't just scan for known malware, it uses multiple analysis techniques to detect brand new threats and potential privacy risks in legitimate apps, and Norton Security and Antivirus uses this information to warn you of dangerous applications before they can cause any problems.
The results are often impressive, with Norton detecting 100% of sample threats in AV Comparatives' recent test of 200+ Android security apps.
Norton Security and Antivirus also has what seems to be a strong set of anti-theft features, including the ability to remotely lock, wipe or locate a stolen device via SMS. Check the small print, though, and you'll find these don't work on Android 4.03 or later.
The main limitation here is the lack of browsing protection. You can avoid dangerous websites to a degree by using Norton's Safe Search tool, but full-strength SafeWeb filtering – Norton's excellent website reputation technology – is only available in the paid Premium edition.
British-based Sophos is a veteran security company who has been developing antivirus solutions since 1985. It's spent most of its life working on products for business, but the company has also branched out into the consumer market, allowing you to try many of its technologies for free.
Sophos Mobile Security is a very complete security app which gives you everything you need to keep your Android app safe, with no ads, annoying restrictions or constant demands to upgrade.
Malware protection includes automatic scanning of apps as they're installed and an option to schedule scans of apps and storage. The results are as reliable as you'll get anywhere, with both AV Test and AV Comparatives reporting a 100% detection rate for Sophos in their latest Android security tests.
The app also scores well for browsing protection, with intelligent blocking of malicious URLs and a Secure QR Code Scanner to prevent you being directed to dangerous sites.
There are enough bonus extras to replace a library of security apps: anti-theft and remote control via SMS messages; password protection for sensitive apps; advisors to make smart privacy and security suggestions; spam protection to block unwanted calls; a KeePass-compatible password manager, and a Managed Mode which allows all Sophos-equipped devices to be monitored and managed from a central location.
Sophos Mobile Security detects malware based on virus definitions which are updated once a day. That's not quite as effective as definition-free products such as Bitdefender Free Antivirus, as they detect threats in the cloud, ensuring you're protected against the latest dangers just as soon as they're discovered.
Sophos' 100% malware detection rate in testing suggests you're not going to see much improvement elsewhere, though, especially when you factor in its extra layers of security. Well worth a try.