System Informer is a free, powerful, multi-purpose tool that helps you monitor system resources, debug software and detect malware.
Features:
- A detailed overview of system activity with highlighting.
- Graphs and statistics allow you quickly to track down resource hogs and runaway processes.
- Can’t edit or delete a file? Discover which processes are using that file.
- See what programs have active network connections, and close them if necessary.
- Get real-time information on disk access.
- View detailed stack traces with kernel-mode, WOW64 and .NET support.
- Go beyond services.msc: create, edit and control services.
- Small, portable and no installation required.
- 100% Free Software
Note: it appears to be the successor of Process Hacker.