This software detects computers that haven't received hotfix updates for a specified timeframe.

While it's not a substitute for a full-fledged patch management reporting, it's an excellent start to diagnose various issues such as SCCM software updates not installing on clients, WSUS stopped working, or Windows updates failing to install for any reason. The tool under review is called Action1 Free Edition.
Action1 enables IT workload automation and orchestration of job scheduling. It allows you to run manual and scheduled batch processes and actions centrally across the entire network. The software is a complete SaaS with an online web-based interface, so you don't need to install any management tools.
Action1 discovers all endpoints in seconds and allows you to manage your entire network by running queries and executing actions in plain English. With basic functionality, the tool has zero cost. Therefore, you can get started with network management without incurring any expenses.
Version 2.5: Shows computers which have not been updated (hotfixes have not been installed) for a certain number of days