Free OBJ (.obj) to STL (.stl) 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
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 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 | STL | |
|---|---|---|
| Geometry | Polygon mesh | Triangle mesh |
| Units | No | No — unitless numbers |
| Colors & materials | Via MTL sidecar | No |
| Animations | No | No |
| Typical use | DCC tool interchange | 3D printing |
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 .obj file never leaves your device, which makes it safe for confidential designs.
Yes — parts and assembly hierarchy are preserved where STL 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.
The OBJ importer reads the geometry file alone; an external .mtl sidecar and its texture files are not resolved, so that material detail is absent before export. The STL result also has no units, colors, material data or part names, so keep the source alongside it.
Which file format should you actually print from? A practical ranking of STL, OBJ, 3MF and AMF for FDM and resin printing, with free conversion tools.
Most online CAD converters upload your intellectual property to unknown servers. Learn what actually happens to uploaded files and how client-side conversion avoids the risk.