Heimdal Free is a program that includes 3 layers of defense to protect you from malware and other threats. First it scans your computer for outdated programs and silently updates them so you are using the latest and most secure versions. Second, it scans network traffic for malware downloads and threats and blocks them from your computer. Finally, if malware is able to get on to your computer it blocks them from accessing the Internet so they are unable to exfiltrate data or connect to command & control servers.
Secunia PSI is a tool that can be used to monitor your installed applications for new updates. When started, Secunia PSI will scan your computer for applications and install any updates that are available for them. This allows your computer to remain secure from possible vulnerabilities in your installed programs.