Test Comparison - What is the Best Free Online Antivirus Scanner?

Some of our readers asked us to test the most popular free antivirus scanners found online. Since such scanners are useful in providing a good second opinion, without having to install a fully-featured security product, I thought it is worthwhile to evaluate such products. I finally found a full day for testing the 10 most popular online security scanners. It took quite a bit of work but I have some exciting results to share. Don’t hesitate to read this article and learn about the best free online antivirus scanner.

The Antivirus Scanners Being Tested

To choose the products included in this test, I used our list with the Top Internet Security Suites of 2011-2012. For all the vendors whose products received our top two badges - Buy for Everyone and Buy for Geeks - I searched to see if they offer a free security scanner. The products I ended up including in this comparison are the following: Bitdefender QuickScan, BullGuard Online Scanner, Comodo Cloud Scanner, ESET Free Online Scanner, F-Secure Online Scanner, Kaspersky Security Scan, McAfee Security Scan Plus, Norton Security Scan, Panda ActiveScan and Trend Micro HouseCall.

I quickly learned that many products are no longer classic online scanners you can run in your Internet browser. Quite a few security vendors now offer standalone antivirus scanners you need to download and install on your computer. They can be run alongside your other security products, without causing conflicts or performance issues. They can be used whenever needed to provide a quick second opinion on your system’s security status.

VERY IMPORTANT NOTE: This test does not include any fully-featured security product. It is about free tools you can use to scan and evaluate the security of your system. These tools cannot and should not replace proper security solutions such as antivirus, anti-spyware and firewall solutions. They should be used only to complement a real security product or to help you identify what's wrong with a system that is suspected of having problems with malware.

The Tests that Were Performed

First, I recorded how each product is designed: if it is a true online scanner, a standalone application or a hybrid between the two. I tried to record as well as possible, the size of each product, and what you need to get it working.

After I installed all the available products, I ran several pieces of malware to infect my test system. I also plugged in an infected USB memory stick. Then, I browsed several dodgy sites that store cookies you don’t want to have on your computer or try to install different forms of malware on your computer.

Once I was sure I had a few malware samples running on my system and several infected files being stored, I started using each antivirus scanner, one by one. I tested how fast they scan your system, recorded how many malware samples they detected, what information was provided and the solutions they proposed.

The scans were made on a 30GB partition with 27GB occupied space. The USB memory stick that was plugged in had 1.88 GB of space and only 9 MB of data, consisting only of infected files.

Bitdefender QuickScan

Bitdefender QuickScan is one of the few true online scanners. You can run it from Internet Explorer and it installs only an ActiveX control. However, before you can use it, you must launch Internet Explorer as administrator. Once I pressed the Scan Now button, it took only a minute for the scan to finish.

Bitdefender QuickScan

Unfortunately though, Bitdefender QuickScan only tells if your system is infected or not and shares the name of the first virus found. There’s no other useful information being displayed. The only option you are given is to download and install Bitdefender Internet Security, so that you can learn more and disinfect your system.

While this tool is quick and painless, it doesn’t provide much value to its users. There are better alternatives provided by other security vendors.

BullGuard Online Scanner

What you first notice about BullGuard Online Scanner is that it takes a long time to download and install all the files it needs to function. As other online antivirus scanners, it downloads and install a small ActiveX file. But, before the scan can start, it downloads around 118 MB of data. The transfer speed is slow and you are in for a lengthy wait.

Once that is out of the way, you can perform a quick scan, a full system scan or a custom scan. The quick scan was done in 9 minutes and revealed 2 infected files and 23 tracking cookies.

BullGuard Online Scanner

The full-system scan revealed 15 infected files (just like Panda ActiveScan) and 23 tracking cookies. For each threat, the solution shares its name, the path to the infected file and the status of infection, which is rather strange since infected files can have only one status - infected. :)

BullGuard Online Scanner

Another strange fact about BullGuard Online Scanner is that it doesn’t actively promote BullGuard products. You are given no advice, link, clue on what to do next. You need to scroll down the scanning window to find links to BullGuard products that can help in disinfecting your system.

BullGuard Online Scanner is a decent product which functions well but won’t win any prizes for being special in any way.

Comodo Cloud Scanner

Comodo Cloud Scanner is a standalone application that you need to download and install. Even though it looks good, it offered a surprisingly bad experience. First, there seems to be only one type of scan available. It was over in about 40 seconds and revealed some very surprising numbers: apparently, I had 4178 privacy issues, 135 registry errors, 3461 junk files but no malware on my computer. I was baffled by these numbers.

Comodo Cloud Scanner

A closer look revealed some surprising facts. For example, Comodo counts log files and crash reports generated by Internet browsers as privacy issues. Then, some of the junk files are valid shortcuts placed on the desktop or other places. These are anything but junk files. Last but not least, many of the so called "registry errors" were legitimate registry entries to shared dlls and other files. I was very surprised by the blatant lies reported by this product.

Another surprise was that, when pressing Details for Malware & Suspicious files, Comodo Cloud Scanner made the offer to run another, more in-depth scan. I allowed it to go ahead and scan my system one more time.

After 25 minutes, it reported 1 suspicious file and 2 unknown files. The unknown files were legitimate Windows files while the suspicious file was the uninstall executable file installed by Comodo Cloud Scanner for another product it bundled: Comodo LivePCSupport.

Comodo Cloud Scanner

I laughed so hard. And, to make the joke even bigger, pressing the Help me clean my PC! button opens Comodo LivePCSupport. This product is useless at disinfecting your computer. It only allows you to chat with Comodo technicians or access their online community. There’s not even one link displayed to a product that can disinfect your system.

Comodo Cloud Scanner is a useless product that doesn’t detect any real malware. It only tries to panic its users by reporting false data and an incredibly high number of fake problems.

ESET Free Online Scanner

ESET Free Online Scanner is one of the very few good online scanners available. It runs in Internet Explorer and it installs only an ActiveX control. Before a scan is performed, it automatically downloads the latest signatures to your computer. You can perform a standard full-system scan or a custom scan. For each scan you can customize different aspects such as: whether you want it to remove the threats it finds, if it should scan archives or not or scan for potentially unwanted or unsafe applications. The full-system scan took about 35 minutes and identified 8 infected files.

ESET Free Online Scanner

For each identified threat, it displays its name and file location. I appreciated that, once a scan is performed, you can set it to uninstall the files and add-ons installed on your computer, prior to starting the scan.

ESET Free Online Scanner

Also, ESET’s products are promoted in a discreet and non-intrusive way. ESET Free Online Scanner offers what I expect from a true online scanner and I was pleased with how it performed.

F-Secure Online Scanner

F-Secure Online Scanner is the only scanner that requires Java to be installed on your computer. Before a scan is made, it automatically downloads the latest signature files. Unfortunately, the download process is on the slow side, so you need to arm yourself with a bit of patience.

You can perform quick scans, full-system scans or custom scans.

F-Secure Online Scanner

The quick scan was done in 1 minute and it identified 6 infected files. It turned out to be the most effective quick scan out of all the products that have this feature available. The full system scan was done in 8 minutes and identified 11 infected files. For each identified threat, F-Secure Online Scanner shares the name and a link to see technical details. Using this link takes you to F-Secure’s encyclopedia of viruses, where you can see more information about the identified threat.

F-Secure Online Scanner

F-Secure Online Scanner is capable of disinfecting your system and allows you to send the infected files to F-Secure’s servers, for a closer look. Overall, it is a solid and effective product that will please many users. The only downside about it is that I would have preferred to know also the location of each infected file.

Kaspersky Security Scan

Kaspersky Security Scan is a standalone application you need to download and install on your computer. Its interface is simple, calming and easy to use. You can perform a quick or a full system scan and change the schedule for regular scans. By default, the tool scans your system once per day. You can change the frequency to once every two days and that’s it. There are no other options for scheduling scans.

Kaspersky Security Scan

A quick scan finished in about a minute and revealed only 2 pieces of malware. A full system scan finished in 13 minutes and identified 8 pieces of malware.

Kaspersky Security Scan

When presented with the results, they are split into several sections:

  • System protection issues - shows whether you have an active antivirus installed on your computer.
  • Malware - shows all the infected files that were discovered during the scan.
  • Vulnerabilities - shows if your system is vulnerable to known security issues, due to a lack of updates, etc.
  • Other issues - displays issues with how Windows or Internet Explorer are configured.

When you click on details, you see a report displayed in your default browser with more information about each problem. For malware, you are shown the name of the identified threat and the specific file that was infected. This is useful information that allow you to find and download the appropriate removal tool. Pressing the Fix now button takes you to Kaspersky’s website, where you can purchase one of their security products and disinfect your system.

Overall, I was very pleased with Kaspersky Security Scan. It is simple, easy to use and provides valuable information about the threats being detected. I also appreciated that it doesn’t aggressively market Kaspersky’s product and doesn’t try to create an artificial sense of panic.

McAfee Security Scan Plus

If you carefully read the information shared by McAfee for McAfee Security Scan Plus, you will learn that this product is not really an antivirus scanner, despite what its name implies or what you might assume.

McAfee Security Scan Plus

This tool does not search for viruses. It only evaluates if you have proper antivirus and firewall protection installed. Information which you can easily obtain from Windows 7’s Action Center. The only malware related information it shares, is whether there are some tracking cookies found in Internet Explorer. It functions only as a tool that recommends you to install other McAfee products. Therefore, it provides very little value and cannot be used as a free antivirus scanner.

Norton Security Scan

Norton Security Scan is a desktop application you must download and install on your computer. When you start it, it automatically downloads the latest definitions and detection engine. All-in-all expect to download around 150MB of data. This makes it by far the largest product of its kind.

One thing that you quickly notice about Norton Security Scan is that it is very alarmist. Everything is red, even if your scan is not yet done. Also, it promotes Norton products in a very aggressive way. If you move your mouse over different areas of its window, new commercials are displayed.

Norton Security Scan

This product allows you to make a full system scan or enable or disable scheduled scans, which seem to take place on a daily basis. There’s no way to change their frequency.

The full system scan ended in only 4 minutes and, at the end of it, I was shown a huge warning. Pressing the Fix Now button takes you to a page where you can purchase Norton security products and closes Norton Security Scan. That’s unfortunate if you want to see information about the threats that were detected. The only way to view this information is to run the scan again and press Do Not Fix Threats.

Norton Security Scan

For each detected threat, you are shown its name, exact location, its type and risk level. All very useful information. Norton Security Scan detected 8 infected files and 29 low-risk tracking cookies. It is one of the few products that identified tracking cookies and I consider this a plus.

Overall, Norton Security Scan is very effective at identifying malware but it is very aggressive. When using it, you receive lots of red warnings that try to make you feel insecure and requests to install different Norton products. Using this product can become annoying very quickly.

Panda ActiveScan

Panda ActiveScan proved to be a good online antivirus scanner. As other online scanners, it needs to install only an ActiveX control in Internet Explorer and, before the scan is started, it downloads the latest signatures automatically. You can run a quick scan, a full-system scan or a custom scan.

Panda ActiveScan

The quick scan took about 2 minutes and detected 2 infected files and 15 tracking cookies. A full system scan took 30 minutes and found 15 infected files and 15 tracking cookies. Unlike other products, it seems that Panda ActiveScan also identifies older latent malware, that is not necessarily dangerous in modern operating systems, such as Windows 7. However, users of Windows XP will appreciate this.

For each threat, you are shown its name, the file that is infected, and its type. You can export the report to a text file and, for each malware item, there is an Info link that takes you to Panda’s encyclopedia of malware, where you can read more about what was found. That’s very useful and many will appreciate this.

Panda ActiveScan

If you want to clean the files that were found as infected, the tool allows you to purchase a commercial version of it that has this capability. Even if its interface might look dated, I was very pleased with Panda ActiveScan. It proved to be a very capable online antivirus scanner.

Trend Micro HouseCall

Trend Micro HouseCall is a standalone product you need to download and run on your PC. When you run it, it automatically downloads the latest updates. In total, expect to download around 50MB of data.

Its interface is simple and easy to use. I appreciated that, using the Settings button, you can set it to run a quick scan, a full system scan or a custom scan. It’s the only product in its niche that allowed for custom scans to be made.

Trend Micro HouseCall

The quick scan finished in about 8 minutes and detected 3 infected files. The full-system scan took a total of 118 minutes (yes, that’s correct!) and detected 5 infected files. The wait times were huge and tested my patience greatly. For each piece of malware, you are shown its name, exact file location, its type and risk level.

On the positive side, this is one of the few products that can help you remove the malware it detects. I’m sure many of its users appreciate this feature.

Trend Micro HouseCall

Also, the actions performed during the previous scan are stored and you can revert them, if needed. That’s another great feature unique to Trend Micro HouseCall.

Trend Micro HouseCall is a surprisingly innovative product. It has some great features that other free antivirus scanners do not have. Unfortunately, the product is penalized by its very slow scanning speed.

Overview of the Results

Since I ended up evaluating two different types of products, I chose to split my evaluation in two groups: online antivirus scanners and security scanning applications.

First, you can see the overall picture for classic online antivirus scanners that you can run in Internet Explorer or other browsers.

Best Online Antivirus Scanner

For the security scanning applications, the final evaluation criteria were slightly different. They are summarized in the table below.

Best Free Security Scanner

The Best Online Antivirus Scanner & Security Scanner are...

The verdict is split in two categories as well. If you are looking for a good online antivirus scanner to run in your browser, then F-Secure Online Scanner is your best choice. Once you get it up and running, it will prove to be a solid, customizable product that can also be used to disinfect your system. Also, Panda ActiveScan is a close second place, being penalized only by the fact that you need to purchase its commercial version in order to disinfect files.

Regarding security scanning applications, the situation is pretty mixed. On one hand you have products that are useless, such as Comodo Cloud Scanner and McAfee Security Scan Plus, while others are good but not perfect. For example, Trend Micro HouseCall has the most features, including the possibility to cleanup your system or revert back changes done during the previous scan. Unfortunately its slowness really deteriorates the experience of using this product and many users will be put off by it.

In my view, the best security scanning application is Kaspersky Security Scan. It is a solid, well rounded product that does its job well and doesn’t annoy users with aggressive marketing. Well done Kaspersky!

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About the Author: Ciprian Adrian Rusen
I love technology and I work in IT for more than a decade. I am the co-founder of Digital Citizen and its chief editor. Alongside my work as an editor, I am also an author. I have written and published 7 books, most of them about Microsoft products and technologies. They are translated into more than 12 languages. In 2014, I have been recognized by Microsoft for my technical expertise and involvement in the community with the title of Microsoft MVP - Windows Consumer Expert.