Lotus Notes database file
File type: Database file
An NSG file is a database file used by older versions of Lotus Notes.
It stores data for a Lotus Notes database and is associated with the historical NSG database format.
Found 2 different file type records with the same nsg filename suffix.
File type category:
Database file
Date updated: October 25, 2026
The NSG file extension was used by Lotus Notes versions 2 and 3. Lotus introduced the format because the original NSF file extension had a size limitation. NSG databases supported larger database files.
Later versions of Lotus Notes changed the NSF size limitation, so the separate NSG format was no longer needed. NSG files are therefore mainly encountered as legacy Lotus Notes databases rather than as files created by current software.
Lotus Notes was developed by Lotus Development Corporation and later became IBM Notes. The associated MIME type is application/vnd.lotus-notes.
Try opening the file with IBM Notes, formerly called Lotus Notes, on Microsoft Windows. Because NSG is a historical format, an older compatible Lotus Notes release may be required if a current version cannot open it.
Open the file from within the Notes application rather than treating it as a document in a general-purpose file viewer.
If Lotus Notes can open the database, its database export or replication features may allow the contents to be moved into another Notes database or exported in a supported data format.
Software applications that can open nsg files:
Microsoft Windows
Software applications that can edit nsg files:
Microsoft Windows
Software capable of saving nsg files:
Microsoft Windows
Software apps that create nsg files:
Microsoft Windows
File type category:
Various data file
Date updated: November 3, 2026
The nsg file extension is associated with Nessie, an emulator for the Nintendo Entertainment System, a video game console. Nessie runs on Microsoft Windows.
The nsg file stores data used by Nessie. It is an application-specific data file rather than a Nintendo Entertainment System game file or a general-purpose interchange format.
Open the nsg file with Nessie on Microsoft Windows. If Nessie does not open it automatically, use the emulator's file or data-loading command, where available.
The nsg file is application-specific Nessie data, so it cannot normally be converted to a useful general-purpose format. Use Nessie to access the data, or keep a copy of the original file before attempting any changes.
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