Free STL (.stl) to OBJ (.obj) converter — running entirely in your browser. No upload, no signup, no file limits: your files never leave your device.
STEP · IGES · BREP · STL · OBJ · PLY · GLB · glTF · 3MF · COLLADA · AMF · FBX · 3DS · OFF
STL is the de-facto standard for 3D printing. It describes a model purely as a mesh of triangles — no color, no units, no assembly structure — which makes it simple, universally supported, and the required input for virtually every slicer, from PrusaSlicer and Cura to resin-printer tools.
OBJ is a plain-text mesh format from the world of computer graphics. It stores vertices, normals, texture coordinates and polygon faces, and nearly every 3D application — Blender, Maya, 3ds Max, game engines, renderers — can read and write it, making it a dependable lowest common denominator for mesh exchange.
| STL | OBJ | |
|---|---|---|
| Geometry | Triangle mesh | Polygon mesh |
| Units | No — unitless numbers | No |
| Colors & materials | No | Via MTL sidecar |
| Animations | No | No |
| Typical use | 3D printing | DCC tool interchange |
Yes — free with no accounts, no watermarks and no file-size limits. Conversion runs on your own machine, so there are no server costs behind it.
No. The converter runs entirely in your browser using WebAssembly. Your .stl file never leaves your device, which makes it safe for confidential designs.
Yes — parts and assembly hierarchy are preserved where OBJ supports them, and you can optionally merge everything into a single mesh during conversion.
Yes. Every converted model opens in the built-in 3D viewer with an assembly tree, display modes and section views, so you can inspect the result first.
STL already contains only unitless triangles, with no part names, colors or design history for a converter to preserve. The OBJ result is a single geometry file with no generated MTL sidecar, so it does not carry textures or material definitions.