Free antivirus apps don't do much more than scan your device for existing threats. And because they are free, you can expect a lot of ads and a bit of slowdown because of the number of resources they use. After testing several free antivirus apps, my top pick is Sophos Intercept X for Mobile (opens in new tab) because of the extra security tools it comes with and how well it finds malware without causing too much drag.

Best Overall: Sophos Intercept X for Mobile

Sophos Intercept X for Mobile

Best free protection for mobile devices

Reasons to buy

Reasons to avoid

This app blocks calls and filters text messages for malicious links. Its QR scanner checks each link to make sure they are safe before connecting you or allowing a file to download. Sophos' anti-theft tools let you remotely access stolen phones to wipe data or reset passwords, send text commands to the thieves and track where your phone is.

Sophos has a system scanner that looks for other security issues with your device and helps you secure them. This could be an outdated program or an app running in the background that doesn't need to be. Sophos also isn't overly ad-heavy, so you're not distracted too much or experience slowdown of your phone.

The app itself isn't the easiest to figure out how to use. It took me some time to figure out where all the tools are located and how to either enable or disable them. But it is impressive to see the number of features you get with this free app.

Includes VPN: Avast Antivirus

Avast Antivirus

Shield device location with a VPN

Reasons to buy

Reasons to avoid

This mobile security program has a data shield to protect photos, contact information, and other sensitive files from being seen or swiped by unauthorized apps and hackers. It stops malware before it attacks your device and blocks phishing schemes. It's straightforward to use with most tools displayed on the dashboard front and center. And during virus and security scans, I didn't experience much slowdown on my devices.

Avast Antivirus has web protections that help identify dangerous websites known to harbor malicious files and downloads. This is an excellent way to stop threats from infecting your device, though this isn't a true, real-time blocker like those included with Avast's paid version. You also get a VPN with this app to help shield your device from adware and other internet trackers.

Avast does have ads, because it is a free program, and it requires a lot of permissions to be given to access every part of your cell phone or tablet. In some ways, this made me uneasy since it doesn't have real-time protection. But I was also impressed with how well it scanned files looking for malware, junk files, and cache to clean up.

Photo Vault: AVG AntiVirus Free

AVG AntiVirus Free

Guards photos from prying eyes

Reasons to buy

Reasons to avoid

AVG AntiVirus includes a photo vault that encrypts your files so they can't be taken hostage by ransomware or accessed without your permission. The VPN connection hides your device's location and information from adware and internet trackers.

This app doesn't have real-time malware protection, but it does have deep scans to locate any problems on your cell phone or tablet. It helps you get rid of junk files, so your device runs faster, and will even scan web sites and let you know if they are known to have malicious files or links on them.

There was a noticeable lag on my phones while AVG was installed, especially during virus scans. It became increasingly frustrating having to wait a bit longer for apps to open, upload attachments to emails, or while playing a game. While I like how thorough AVG scans for problems, it's too frustrating for me to endure the slowdown.

Basic Protection: Bitdefender Free Antivirus

Bitdefender Free Antivirus

Basic, yet powerful protection

Reasons to buy

Reasons to avoid

All this app does is scan your device for malware that may have made it onto your phone or tablet. There isn't a safe browsing feature or phishing filters to stop attacks, but its autopilot scans your device often enough to catch threats before they become a problem. You don't have to use the autopilot feature, instead, starting and stopping scans manually. And Bitdefender dives deep into all your files on removable SD cards to ensure nothing is hiding anywhere.

During my tests of Bitdefender Free Antivirus, I was able to keep working on my devices without worrying about my system running slower or lagging during a game. I didn't realize there was a scan going on until Bitdefender notified me that it was done. Also, although Bitdefender is a free antivirus app, there aren't a lot of ads that get in the way.

The big reason Bitdefender Free Antivirus doesn't take the top spot is that it doesn't offer any other tools. It doesn't have a VPN or anti-theft tools that some of the other apps include. But if you don't need the extra features, then I highly recommend Bitdefender for all your devices.

System Scanner: Lookout Security

Lookout Security

Track your phone with anti-theft tools

Reasons to buy

Reasons to avoid

Depending on the device you have and your cell phone provider, Lookout Security may have already come installed on your phone. This antivirus program frequently scans your phone for any malware and helps you remove it. It also shows you which apps are running in the background and draining your device's battery.

Lookout's system advisor continually looks at your operating system for any root issues that may be interfering with how your phone or tablet is working and will help you fix them to secure your device from hackers and other snoops. And it includes some anti-theft tools, including a device locator and remote lockdown.

There aren't a lot of other tools or features included with the free version of this app. You can purchase the Premium version that includes file backup and a VPN. But several users find these tools don't work very well and prefer the free version, even without these extra features.

Adware Removal: Malwarebytes Security

Malwarebytes Security

Scans deep and removes adware

Reasons to buy

Reasons to avoid

This basic antivirus app won't stop malware infection but does an excellent job of rounding up malicious files, including adware, already on your devices. It doesn't use a lot of resources, so you won't experience slow down while Malwarebytes is running. Another perk of Malwarebytes is, despite being a free antivirus program, it's completely ad-free.

Malwarebytes detects and stops ransomware before it can encrypt and hold hostage your files and programs. It also recognizes phishing schemes, even in emails, and will alert you of them before you click through or provide personal information.

You can try the Premium version for additional tools, including real-time detection and prevention of malware. Still, you will have to pay for these additional features after the trial period ends.

Final thoughts

I've chosen Sophos Intercept X (opens in new tab) as the best free antivirus app for Android because it does an excellent job of scanning for threats that have made it onto your device. It didn't cause a slowdown on my test devices, plus it comes with an impressive list of features for a free program. These include anti-theft tools that remotely locate, secure, and wipe sensitive information. Sophos also checks links and QR codes before allowing them to open or download, just in case there is a threat attached to it. And while it may take a moment or two to figure out how to use the program, overall, Sophos gives you more security for free.

While cell phones are still pretty secure, there is more and more malware being developed explicitly targeting mobile devices. Most free apps come with several in-app ads trying to get you to upgrade to a paid version. Also, most free antivirus apps scan your device for malware after it has become infected rather than stopping threats before they download or attack. I do have a healthy list of the best antivirus apps for Android that have been thoroughly vetted. But that doesn't mean you can't get some reliable protection from a free app.

Credits — The team that worked on this guide

Nicole Johnston writes for multiple Future Publishing brands, including Android Central, covering primarily internet security and privacy programs. She has over 13 years of research and writing experience in both the public and private sectors, including seven years testing and reviewing consumer products and five evaluating antivirus software, parental controls, VPNs, and identity theft services. Nicole is mom to 10 kids.