Reflex is described as 'small tool to watch a directory and rerun a command when certain files change. It's great for automatically running compile/lint/test tasks and for reloading your application when the code changes' and is an app in the Development category. There are three alternatives to Reflex for Linux, Mac, Self-Hosted solutions and Windows. The best alternative is PM2, which is both free and Open Source. Other great apps like Reflex are nodemon (Free, Open Source) and entr (Free, Open Source).
Advanced process manager for production Node.js applications. Load balancer, logs facility, startup script, micro service management, at a glance. PM2 plus for monitoring via online $39/month - 8 process $69/month - 16 process $129/month - 32 process
nodemon is a tool that helps develop node.js based applications by automatically restarting the node application when file changes in the directory are detected. nodemon does not require any additional changes to your code or method of development.