Making sure that a web application is running should be a primary concern for us. Big companies like to brag about 99.9 percent uptime for their applications, and this should be the goal for everybody, really.
To monitor live applications and restart them when they crash, there are a number of solutions, including native OS ones:
mon: This tool (https://github.com/visionmedia/mon) is a simple single process-monitoring program written in C by the creator of Expressforever: This tool (https://www.npmjs.org/package/forever) is a Node solution that has been battle-tested at Nodejitsu and is actively maintainedmonit: This tool is a utility that monitors services on a Unix system
It's important to have such a monitoring tool for our Express applications, whether it's one of the preceding tools or another one. Without such a tool, we will have to manually take care of restarting the application when it crashes.