nsf is: Nsf extension is associated with Lotus Notes Database. You have chance to open nsf files with IBM Lotus Notes.
NSF extension stands for database files which created by lotus notes software. Lotus notes is an IBM firm`s product. The same file type is used with other database softwares which are under Lotus brand. To get detailed information about the Lotus software, please check the following web page.
Nsf File format viewers or openers
IBM Lotus Notes
Nsf File related links.