Chkrootkit is a free, open source application designed to help system administrators detect and remove any malicious rootkits that might be installed on their systems. A rootkit is a type of malicious software that is designed to hide itself from normal system processes, allowing it to remain undetected on a system for extended periods of time. Chkrootkit is designed to scan a system for any known rootkit signatures, as well as any suspicious system activity that could be indicative of a rootkit infection. It can also detect privilege escalation attempts, malicious system modifications, and other suspicious activities. Chkrootkit can be run as a standalone application, or through a web interface, and is available for most major operating systems.
Chkrootkit is a tool for Linux. IceSword is for Windows. So it is not an alternative at all.