BSP to STEP Converter
FileFlip converts BSP to STEP 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 BSP file to STEP?#
- Drop your BSP 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 STEP 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 STEP file. Your browser writes it straight to your downloads folder, because there was never a server holding it.
Does converting BSP to STEP lose quality?#
Not in the sense of pixels or samples. Converting BSP to STEP rebuilds the file in STEP's own model rather than re-encoding it, so everything STEP 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 BSP files online?#
Yes, because nothing is uploaded. FileFlip converts BSP 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 BSP to STEP actually does to the file#
Converting BSP to STEP 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 skeleton and animation.
| Engine | Assimp |
|---|---|
| Conversion path | One step: BSP → STEP |
| 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 | Dropped | The target format has nowhere to put it. |
Worth knowing before you start:
- if the source carries a skeleton or animation, this target has no place to store it
What is a BSP file?#
A BSP file is a compiled Quake III Arena level: an entire map's world geometry, pre-partitioned into a binary space tree, along with its lightmaps, texture references and entity placements, not a model of a single object.
Use BSP to ship or run a compiled Quake III Arena level; the original engine or a source port loads it together with its PK3 to render the map.
Convert a BSP file mainly to inspect or reuse its geometry outside the original game, since the format isn't meant to be edited directly; going back to the level editor's source .map file is the normal way to make changes.
What is an STEP file?#
An STP file holds a STEP product model in ISO 10303's plain-text exchange syntax, encoding exact boundary-representation solids, surfaces and curves rather than a triangulated mesh.
Use STEP whenever exact CAD geometry, not an approximated mesh, needs to move between two different CAD systems.
Convert a STEP file to a mesh format like STL or OBJ once the model is finished and only needs to be viewed, rendered or 3D printed rather than edited as a solid.
BSP to STEP questions people ask#
What is a BSP file?
A BSP file is a compiled Quake III Arena level, holding the map's entire world geometry pre-sorted into a binary space partition tree along with its lightmaps and entity placements. It's a level, not a single model, so opening one gets you the whole map's geometry rather than a prop.
Can I get a single object or prop out of a BSP file?
Not directly. A BSP stores one specific map's geometry already merged and partitioned for that layout, so there's no clean way to pull out an individual piece without rebuilding the partition and visibility data from source. The original .map file the level was compiled from is the format actually meant for editing.
What opens BSP files today?
The open-source ioquake3 engine and games built on it, like OpenArena, load BSP files exactly as Quake III Arena did, and level editors such as GtkRadiant and NetRadiant compile and inspect them directly.
What does STP stand for?
STP is the file extension for STEP, the Standard for the Exchange of Product model data, formally ISO 10303. It's the neutral format mechanical CAD systems use to hand solid models to each other.