What is a .NSF file?
The .nsf extension is shared by Lotus Notes databases and NES Sound Format chiptunes.
NES Sound Format
- What it is
- A NES Sound Format chiptune - ripped 6502 audio code from a Nintendo NES / Famicom game. Analyser reads the song count, load/init/play addresses and the tune metadata.
- How to tell it apart
- An NSF chiptune begins with the ASCII magic NESM.
- Did you know
- An NSF holds the actual 6502 machine code from the game's sound engine, so playing one means emulating the NES processor and audio chip in real time.
- The format was designed by Kevin Horton, who first called it NESM and built it to play back on a custom hardware device of his own.
- The extended NSFe variant, devised by the developer Disch for his NotSo Fatso player, adds the track names, timing and fade-outs the original header lacked.
Lotus Notes database
- What it is
- An IBM / HCL Lotus Notes and Domino database - mail, documents and design elements. Analyser identifies it from its header.
- How to tell it apart
- A Notes database has its own binary header (not NESM).
- Did you know
- Lotus Notes .nsf files store documents, mail and whole apps together, and some corporate ones have been in continuous use since the early 1990s.
- Lotus Notes was built by Ray Ozzie's Iris Associates and first released in 1989, and the NSF extension stands for Notes Storage Facility.
- IBM bought Lotus in 1995 and then sold Notes and Domino to India's HCL in a deal completed in 2019, so one .nsf has outlived two owners.
- Depth of analysis
- .NSF is an identification-grade format: Analyser recognises it from its bytes and decodes the header metadata it carries, rather than opening it in a full viewer. Formats that do get a full viewer are marked "Full" on the formats page.
- Open a .NSF file
- Drag a .NSF file onto the Analyser home page (or tap to pick one). It is identified entirely in your browser - nothing is uploaded, there is no account, and it works offline once installed.