ProcessMonitor from Microsoft (used to be Sysinternal) can record real-time access to files (and more)
https://technet.microsoft.com/de-de/sysinternals/processmonitorhttps://docs.microsoft.com/sysinternals/downloads/procmon
This is useful if you want to record which files an application has accessed over time, e.g. during startup.
ProcessExplorer (a task manager replacement) can show the currently open files for an application
https://technet.microsoft.com/en-us/sysinternals/bb896653.aspxhttps://docs.microsoft.com/sysinternals/downloads/process-explorer
Using the "Find handle" option it's possible to find the applications accessing a specific file.
