STEP to OBJ converter
Drop your .step / .stp file — we convert it to .obj right in your browser. Files never leave your computer.
Why convert STEP to OBJ?
OBJ is the hand-off between CAD and rendering. STL cannot carry materials; OBJ can — via a companion .mtl file that Blender, KeyShot, and V-Ray all read. When mechanical data needs to meet a render artist, OBJ is the canonical bridge because it's simple, text-based, and universally supported.
Who runs this conversion
Product visualisation artists rendering marketing hero shots from CAD, Blender hobbyists importing mechanical parts into character scenes, and engineering teams preparing technical illustrations. Also common when the downstream tool is older (KeyShot 7, pre-2020 Blender) and lacks a good STEP importer.
Things that commonly go wrong
- OBJ has no face groups equivalent to STEP bodies — surfaces melt into one mesh unless you split assemblies in CAD first.
- Normals occasionally flip on certain CAD kernels; flat shading masks it but Cycles / PBR render it instantly.
- Large assemblies produce multi-megabyte OBJ text files — consider GLB when file size matters.
Technical note for this tool
OCCT tessellates the B-rep, Three.js writes a single .obj with per-vertex positions and normals. Materials are stubbed as a default grey — re-authoring PBR is expected in your DCC.
STEP vs OBJ— what's the difference?
ISO 10303 boundary-representation CAD format — the industry standard for exchanging precise, parametric solid models between engineering tools.
- Exact curved surfaces (NURBS / B-rep) — no tessellation loss
- Assembly hierarchy, part names and metadata preserved
- Supported by every major MCAD tool (SolidWorks, Inventor, Fusion, Creo, NX…)
- Open, vendor-neutral ISO standard
- Not directly consumable by 3D printers or game engines
- Files are larger and slower to open than mesh formats
- Requires a CAD kernel to read — no native browser support
Human-readable Wavefront mesh format — ubiquitous in 3D graphics, game art, and asset pipelines. Pairs with a .mtl material file.
- Supported by virtually every 3D tool (Blender, Maya, 3ds Max, Unity, Unreal…)
- Plain-text, easy to diff and hand-edit
- Keeps UV coordinates and vertex normals, unlike STL
- Material references via companion .mtl file
- Text format — larger on disk than binary meshes
- No scene hierarchy, no animation, no skeletons
- Materials live in a separate file; easy to lose
Deeper context on the formats
STEP — where it came from
Standardised as ISO 10303 in 1994 to replace the aging IGES format. Application Protocols AP203 (configuration-controlled design), AP214 (automotive), and AP242 (modern merge of both) define what data travels with the geometry — AP242 is the current default for new exports and is what most fabs expect in 2026.
- Assemblies exported with external references break when the .step file is moved without its companion files — always export as a single-file package (AP242 XML or monolithic .step).
- Kernel-to-kernel round-trips (e.g., Inventor → STEP → Fusion → STEP) can introduce tiny sliver faces and edge-tolerance drift; keep the original parametric file as the source of truth.
- PMI (product manufacturing information — GD&T, annotations) only rides along in AP242 — older AP203 exports strip it silently.
Real-world use: Mechanical suppliers quote from STEP, contract manufacturers program CNC toolpaths from STEP, and electronics vendors publish component 3D models as STEP on Digi-Key and Mouser. Any time a mechanical engineer hands off a design to a machine shop or an injection-mold vendor, it ships as STEP.
OBJ — where it came from
Created by Wavefront Technologies in the late 1980s for their Advanced Visualizer software. When Wavefront was absorbed into Alias (then Autodesk), the format stayed public and became the lingua franca for academic 3D research, hobbyist modeling, and early game art. Its ASCII simplicity is why every graphics textbook still ships an OBJ example file.
- The .mtl material file must travel with the .obj — ship them as a zip or the textures will vanish on the other side.
- Negative indices and per-face normals exist in the spec but many importers silently misread them. Re-export from a round-trip through Blender if a downstream tool complains.
- Triangulate before export if the target is a game engine — Unity and Unreal OBJ importers choke on n-gons.
Real-world use: Computer-graphics research papers still use OBJ as the reference format for meshes. Hobbyist marketplaces (TurboSquid, CGTrader free tiers) distribute OBJ + MTL packs. Photogrammetry pipelines (Meshroom, RealityCapture) output OBJ as the portable intermediate. It is still the safest format to hand to a stranger who just said "I need a 3D model."
How to convert STEP to OBJ
- 1Drop a .step or .stp file on the page. The CAD kernel runs in your browser via WebAssembly — nothing uploaded.
- 2Preview the tessellated model in 3D. Confirm the hierarchy via the Scene Tree sidebar.
- 3Click Download .OBJ. Pull the file into Blender, Maya, 3ds Max, Unity, or Unreal.
FAQ
Why go STEP → OBJ instead of STEP → FBX or GLB?
OBJ is the lowest-common-denominator mesh format — every DCC and renderer reads it. If you're shipping CAD to a 3D artist who doesn't use a CAD tool, OBJ is the safest format. For web / AR, prefer GLB.
Is my STEP file uploaded anywhere?
No — everything runs in-browser using occt-import-js (OpenCascade WASM) and Three.js' OBJ exporter.
Will the OBJ keep part / assembly names?
OBJ has 'o' (object) groups but no real hierarchy. Part names from the STEP appear as groups; nested assemblies are flattened.
Will the OBJ have UVs or a .mtl file?
No UVs (STEP has none to start with — it's B-rep) and no .mtl (no materials in STEP either). Assign in Blender / your DCC post-import.
What about curved faces?
STEP's exact NURBS surfaces get tessellated into triangles during export. This is intrinsic to moving from B-rep to mesh, not a limitation of this tool.