The best free security software 2017

Reliable antivirus is essential for any internet-connected PC, but you can bolster your protection with additional security software that runs alongside it.

Your security software should also protect you from malware – programs that don’t behave like viruses, but are nevertheless a nuisance and a threat to your security. All it takes is forgetting to uncheck a box when you download an otherwise legitimate program, and your PC is compromised.

Your main security software must provide real-time scans to help you avoid an infection in the first place, but on-demand scanners also have their place, identifying  and removing any malicious software if your PC has started to behave strangely.

Your online accounts are a particularly juicy target for criminals too, so it’s also wise to use a password manager and generator to create strong logins and store them in a secure vault. 

We’ve ranked the best free security software in order of priority, starting with strong general purpose packages, through to preventative tools for specific threats. Combining several of these will enable you to create your own free security software suite, but bear in mind that you should only install one antivirus tool at a time.

Avast Free Antivirus makes an excellent foundation for your PC security toolkit

1. Avast Free Antivirus

Avast's powerful security software safeguards your PC from viruses and other threats the moment they appear

Avast Free Antivirus has millions of users, which helps it identify threats as soon as they appear. It scans your PC in real time, and if it comes across a piece of code that looks suspicious, it’s sent to Avast’s labs for testing. If it’s found to be malicious, Avast creates a ‘vaccine’ to eliminate it, which is then sent to every user worldwide.

Avast Free Antivirus can remove unwanted browser extensions and toolbars, which are easy to accidentally install if you often download free software, and there’s also a program updater to patch any recently discovered vulnerabilities in your installed software. It even includes a password manager to keep your logins secure. 

Avast Free Antivirus the most powerful and comprehensive free security software suite around, and the perfect foundation for your online safety toolkit.

Review and where to download: Avast Free Antivirus

Provided you deactivate real-time scanning, Malwarebytes will run happily alongside your regular antivirus software for enhanced security

2. Malwarebytes Anti-Malware

Supplement your core security software with on-demand malware scans

Malwarebytes Anti-Malware runs in tandem with your main security software, providing specific protection from threats other than viruses.

The free edition of Malwarebytes Anti-Malware gives you reliable protection for malware and spyware, as well as rootkits, which give software access to crucial parts of your system without your permission. 

The free edition of Malwarebytes Anti-Malware gives you a two-week taster of its premium features, including real-time scans, and protection from malicious sites, exploit attacks and ransomware (which it differentiates from other malware).

Once that trial period is up, you’re left with a no-frills on-demand scanner that’s ideal for removing unwanted software and identifying the cause of strange browser behaviour or taking back control of your browser if it’s been hijacked by adware.

Review and where to download: Malwarebytes Anti-Malware

Strong passwords are essential for protecting your online accounts. Keepass generates strong logins and stores then in an encrypted vault

3. Keepass Password Safe

Free security software that keeps your logins under lock and key

With so much of our data now stored online – including work, photos, emails, bank account details – strong passwords have never been more important. Unfortunately, the sheer number of online accounts necessary for everyday life means it’s hard to think up and memorize a different strong password for every service.

KeePass Password Safe does the hard work for you, and stores the resulting strong passwords in an encrypted vault protected by a master login or key file. 

KeePass encrypts usernames, passwords and notes using the Advanced Encryption Standard (AES) and Twofish algorithms, and they remain encrypted while the program is running so they won’t be cached to disk. Unlike Avast Free Antivirus’s built-in password manager, KeePass is portable, so you can carry it on a USB stick and it won’t save anything to your Windows registry.

Best of all, because it’s open source, it’s in constant active development and any security vulnerabilities can be patched the moment they’re discovered.

Download here: KeePass Password Safe

If you're faced with a PC suffering a malware infection, Emsisoft Emergency Kit might be the magic bullet you need

4. Emsisoft Emergency Kit

Emergency security software to save your bacon if your PC is already infected

If your antivirus software has failed and your PC’s security has been compromised, you need Emsisoft Emergency Kit.

Like Keepass, Emsisoft Emergency Kit can be saved to a USB stick and run on any PC without being installed (somewhat confusingly, it does have an ‘installer’, but this just extracts the necessary files and saves them to a location of your choice).

Not only does Emsisoft Emergency Kit check for viruses, trojans and worms, it also looks for malware on your PC, including adware, spyware and keyloggers. Bear in mind that these threats are constantly changing, so you’ll have to wait a minute for the security software to update its database of definitions before you can begin scanning.

Emsisoft Emergency Kit won’t conflict with any existing antivirus software on your PC, making it a great little tool to keep on hand. Even if you never need to use it yourself, it might be a lifesaver for a friend or family member who’s a little less cautious about their online security.

Review and where to download: Emsisoft Emergency Kit

It's easy to end up with security-compromising extra software on your PC. Unchecky makes sure you don't miss any authorization checkboxes when installing new programs

5. Unchecky

Uncheck tick boxes automatically to catch malware before it can install itself

Unchecky won’t detect or remove malicious programs, but it can help you avoid installing them in the first place by automatically unchecking the boxes in software installers and alerting you if the app you’re installing is bundled with something else.

As security software, Unchecky isn’t perfect – it doesn’t pick up all unwanted programs, and some installers try to catch you out by taking an unchecked box as consent – but it’s nevertheless a useful tool in your PC security arsenal.

Combined with a common sense approach (only download software from a source you trust, select a ‘custom install’ option if it’s offered, and read each step of software installers carefully), it will help protect you from unwanted extras that pose a threat to you online.

Download here: Unchecky