PRJ to GLB Converter
FileFlip converts PRJ to GLB 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 a PRJ file to GLB?#
- Drop your PRJ 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 GLB 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 GLB file. Your browser writes it straight to your downloads folder, because there was never a server holding it.
Does converting PRJ to GLB lose quality?#
Not in the sense of pixels or samples. Converting PRJ to GLB rebuilds the file in GLB's own model rather than re-encoding it, so everything GLB 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 PRJ files online?#
Yes, because nothing is uploaded. FileFlip converts PRJ 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 PRJ to GLB actually does to the file#
Converting PRJ to GLB 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.
| Engine | Assimp |
|---|---|
| Conversion path | One step: PRJ → GLB |
| 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 | Sometimes | Survives for some files and not others. |
| Textures | Sometimes | Survives for some files and not others. |
| Skeleton and animation | Sometimes | Survives for some files and not others. |
What is a PRJ file?#
A PRJ file from 3D Studio is a project variant of Autodesk's chunk-based 3DS format, the same binary structure with a different top-level chunk marking it as a working project rather than an exported mesh.
Use PRJ only when working directly in original 3D Studio DOS project files rather than their exported meshes.
Convert PRJ to OBJ or glTF to get the mesh into anything modern, since current tools target 3DS or newer formats rather than the old project files.
What is a GLB file?#
A GLB file is glTF's binary packaging, developed by the Khronos Group, wrapping the JSON scene description together with its geometry buffers and textures into one self-contained file instead of a JSON document with separate buffer and image files beside it.
Use GLB whenever a model has to be handed to a web viewer, AR app or game engine as a single upload.
Convert GLB back to glTF's JSON form only when something inside the file needs to be read or edited directly.
PRJ to GLB questions people ask#
What is a PRJ file from 3D Studio?
A PRJ file is a 3D Studio DOS project, using the same chunk-based structure as a 3DS file but marked as the working project a 3DS mesh gets exported from, rather than the exported mesh itself.
Is a 3D Studio PRJ file the same as an ArcGIS PRJ file?
No, they're unrelated despite sharing an extension. A 3D Studio PRJ file is binary 3D scene data, while GIS software like ArcGIS uses .prj for a plain-text coordinate-system definition. The two need to be told apart by their source, not their extension.
What's the difference between a PRJ and a 3DS file?
Both use 3D Studio's chunk-based format, but a 3DS file is the exported mesh while a PRJ file is the working project, which can carry additional light and camera chunks that a plain 3DS export doesn't.
Can I open a GLB file directly on my phone?
Android's Scene Viewer opens a GLB file straight into an AR view without a separate app, since it's built to consume glTF's binary form directly. iOS's AR Quick Look expects USDZ instead, so a GLB usually needs converting first to view in AR on an iPhone.