ESET Online Scanner is an excellent free tool to detect threats without the need to install antivirus software. It utilizes the same scanning technology as ESET Smart Security or ESET NOD32, but it works only through a browser. It is able to scan a variety of areas, including autostart locations as well as areas for booting and the registry. It can also repair issues during a reboot, and also rescan files that were previously believed to be infected. It does not, however provide real-time security.

The interface is simple and easy to navigate. Its main window displays a list of detected threats including their names and descriptions. The user is offered the option of either removing or remove the threats that are identified as well as to create a customized scan profile to search specific folders and files. The program can also be used offline, however an internet connection is required to download the required signatures and for completing the initial update.

The program is able to detect various types of malware, such as viruses, Trojans or spyware, as well as adware and other potentially unwanted programs. It can remove rootkits, which are not always removed by other scanners. It may take a while to complete a full scan, and the software is heavy on the CPU. It is not able to scan encrypted or password-protected files and is not able to detect sophisticated zero-day malware. It is best used as a second-opinion scanner along with other antivirus software. A free one-time scan is available, but future scans board portals comparison and fixes need to be paid for.