NFF to STL Converter
FileFlip converts NFF to STL entirely inside your browser, using Assimp compiled to WebAssembly. The file is never uploaded to a server: it is read off your disk, converted on your own machine, and saved back by the browser. That means no file-size limit, no queue and no account.
How do I convert an NFF file to STL?#
- Drop your NFF file onto the converter at the top of this page, or click it to pick one from your computer. You can add as many as you like.
- Leave the target set to STL and the conversion starts on its own. FileFlip downloads 11.2 MB of WebAssembly the first time and nothing after that, then runs Assimp on your own machine.
- Save the STL file. Your browser writes it straight to your downloads folder, because there was never a server holding it.
Does converting NFF to STL lose quality?#
Not in the sense of pixels or samples. Converting NFF to STL rebuilds the file in STL's own model rather than re-encoding it, so everything STL can represent comes through exactly and anything it cannot has to be dropped. Expect the geometry to be exact, and anything the target has no place for, such as a rig, to be left behind.
Is it safe to convert NFF files online?#
Yes, because nothing is uploaded. FileFlip converts NFF files inside the browser tab you already have open, using WebAssembly builds of the same engines a desktop converter would install. Your file is read from your own disk into the page's memory, and no request carrying it is ever made.
You do not have to take that on trust. Open your browser's network panel, run a conversion, and you will see the engine come down and your file go nowhere. There is no upload, no server-side copy, no retention window, and no account tied to what you converted.
How FileFlip works lists every engine, its version and its download size, and shows how to check for yourself that nothing leaves your machine.
What NFF to STL actually does to the file#
Converting NFF to STL runs on Assimp, downloads 11.2 MB of WebAssembly the first time and nothing after that, rebuilds the file in the target's own model, and drops materials, textures and skeleton and animation.
| Engine | Assimp |
|---|---|
| Conversion path | One step: NFF → STL |
| Downloaded to your browser | 11.2 MB, once, then cached by your browser |
| Quality | Rebuilt in the target's model |
| You get back | One file |
| Where it runs | In a background worker, so the page stays responsive |
What survives the conversion
| What is in the file | This conversion | Why |
|---|---|---|
| Materials | Dropped | The target format has nowhere to put it. |
| Textures | Dropped | The target format has nowhere to put it. |
| Skeleton and animation | Dropped | The target format has nowhere to put it. |
Worth knowing before you start:
- the target stores triangles and nothing else, so materials, colours, and texture coordinates have nowhere to go
- if the source carries a skeleton or animation, this target has no place to store it
What is an NFF file?#
An NFF file is plain text written to Eric Haines' Neutral File Format, first drafted on October 3, 1988 as part of the Standard Procedural Databases project, listing a viewpoint, lights, a background colour and a handful of primitives like spheres, cones and polygons with one letter code starting each line.
Use NFF only when working with an existing ray-tracing benchmark scene or legacy renderer that already expects the format.
Convert NFF to OBJ when its primitives need to become a mesh that a modern 3D application can open.
What is an STL file?#
An STL file is a triangle mesh created by 3D Systems in 1987 for its stereolithography 3D printers, storing nothing but a flat list of triangle facets and their normals, with no colour, material or unit of measurement attached.
Use STL when the only destination is a 3D printer's slicer, which is all the format was designed to feed.
Convert STL to 3MF when colour, material or unit information needs to travel with the geometry, since STL has nowhere to put any of it.
NFF to STL questions people ask#
What is an NFF file?
An NFF file is a plain-text scene description in Eric Haines' Neutral File Format, listing a camera, lights, a background colour and simple primitives like spheres, cones and polygons. Haines created it in 1988 as part of the Standard Procedural Databases project, a set of test scenes meant to let different ray tracers be compared on identical input.
What software can open NFF files?
NFF has no mainstream viewer today; support is limited to older ray tracers and a handful of 3D libraries, such as Assimp, that kept a reader for benchmark and archival purposes. A general-purpose 3D application is unlikely to open one directly.
Does NFF support textures or materials?
No, an NFF surface is described with only a fill colour, a diffuse and specular coefficient, shininess, transmittance and index of refraction, with no texture mapping at all. That simplicity is what made it easy for different renderers to implement consistently.
What is an STL file used for?
An STL file is the standard input for 3D printer slicing software, storing a model's surface as a list of triangles with nothing else attached. Slicers use it to work out where to lay down material layer by layer.