DaemonFS - DaemonFS is a real time file monitoring software.
Watch 4 Folder - Watch 4 Folder is a simple to use, small and portable tool to monitor folders and file activities.
WatchDirectory - WatchDirectory monitors a file system directory and performs tasks when certain conditions are met.
iWatch - iWatch is a realtime filesystem monitoring program.
FSMonitor - FSMonitor is a macOS app that monitors all changes in the file system, including file creation...
fseventer - Graphically observe filesystem changes using the same underlying API as Spotlight.