NEF spans two decades of Nikon bodies
NEF (Nikon Electronic Format) has been Nikon's RAW container since the film-to-digital transition, and unlike Canon, Nikon never renamed it: a D70 from 2004 and a Z8 both write .nef. What changed inside is bit depth and compression. Older DSLRs wrote 12-bit files around 10 to 20 MB, while a 45-megapixel D850 or Z7 NEF commonly reaches 40 to 55 MB in 14-bit lossless compressed form. That size is the practical problem: a folder of NEFs from one event can outweigh a laptop's free cloud storage, and nothing outside photo software opens them. Converting to JPG locally sidesteps both issues at once, with no upload and no special viewer. For the broader picture of how RAW conversion works across brands, see RAW to JPG, or CR2 to JPG if there are Canon files in the same archive.
Local development built on LibRaw
The decoding here is done by LibRaw, the open-source library that powers RAW support in darktable, RawTherapee and many other photo tools, compiled to WebAssembly and running entirely in the page. It reads the NEF's mosaic sensor data, performs full demosaicing, and applies the white balance your Nikon recorded, so the output is a developed image comparable to the camera's own JPEG rendering. The roughly 1.4 MB decoder loads only when a RAW file is dropped, keeping the page fast for everyone else. Because the whole pipeline is local, second-shooter handoffs, client galleries in progress and family archives never touch a server. Sony files from a mixed kit go through ARW to JPG, and smartphone RAW is handled by DNG to JPG.
Common questions
What happens when a NEF file is developed?+−
A NEF holds the raw output of your Nikon's sensor: one filtered brightness value per photosite, plus the white balance and settings you shot with. Development demosaics those values into full-color pixels and applies that white balance. This tool performs the whole process with LibRaw on your device, so the resulting JPG is a genuinely rendered photo from sensor data, not just the thumbnail extracted from the file.
Are NEFs from the newest Nikon Z bodies supported?+−
Mostly, with one honest caveat. Classic NEF files, meaning everything from Nikon's DSLRs and most Z cameras, convert well. The newly introduced compressed NEF variants from the very newest bodies, such as High Efficiency RAW, may fail to decode. When that happens the tool says so plainly instead of producing a broken image. Uncompressed or lossless compressed NEF from the same camera usually works.
Why can't Windows or my phone show NEF previews?+−
NEF is Nikon's proprietary container, and operating systems only preview it if a matching codec is installed. Windows needs a Raw Image Extension that often lags behind new cameras, and most phones show nothing at all. The data is there; the decoder is missing. Converting to JPG produces a file that every browser, phone, chat app and upload form can display without any extra software.
How does the JPG compare to Nikon's in-camera JPEG?+−
Close enough for delivery and sharing. LibRaw develops the NEF with your as-shot white balance and a standard tone curve, which resembles the camera's neutral rendering. Nikon Picture Controls such as Vivid or Monochrome are not reproduced, so stylized in-camera looks will read flatter. Sharpness and color fidelity come straight from the sensor data, and 90% JPG quality keeps the differences imperceptible in normal viewing.