Convert STL to OBJ online — free, no upload

Convert in both directions

Drop a .stl and download a .obj; drop a .obj and download a .stl. The converter reads the format from the file, runs the conversion in your browser, and the download starts on its own — no button-hunting, no account, no email.

How the conversion works

Both formats describe a triangle mesh — a surface made of flat triangles. STL stores those triangles as raw geometry; OBJ stores the same triangles as a list of vertices and faces (and can optionally carry materials and texture coordinates, which STL has none of). Converting between them is a matter of re-expressing the same triangles in the other format, which the geometry kernel does directly. Cadre's kernel is written in Rust and compiled to WebAssembly, so the whole conversion happens in your tab — your file is never sent to a server.

When you'd convert STL ↔ OBJ

• STL → OBJ when a tool wants OBJ — some renderers, game engines, and importers prefer OBJ, and OBJ is easier to read by hand.
• OBJ → STL when you're heading to a slicer or a 3D printer — STL is the near-universal print format, and many slicers still expect it.

What to expect — honest limits

This is a geometry converter, not a scene converter. STL carries no colour, materials, or texture data, so:

• An OBJ → STL conversion keeps the shape but drops any materials, vertex colours, or UVs the OBJ had.
• An STL → OBJ conversion produces a geometry-only OBJ (no .mtl).
• Multiple objects in an OBJ are converted as a single mesh.

For most print-prep and interchange jobs that's exactly what you want. If you need materials and textures preserved, a mesh tool like Blender is the right call. Very large meshes are limited by your browser's memory rather than a server, so typical print models convert instantly while a multi-hundred-MB scan will be slow.

Want to edit it too, not just convert?

If you also need to resize, cut, or repair the mesh, edit your STL online in the same browser editor — import, change it, and export STL or OBJ when you're done.

FAQ

Is the converter free?

Yes — converting STL ↔ OBJ is free, with no account, no upload, and no watermark on the output.

Does my file get uploaded?

No. The conversion runs locally in your browser via WebAssembly. Your file never leaves your machine.

Does OBJ → STL keep colours and materials?

No. STL is a geometry-only format, so materials, vertex colours, and texture coordinates are dropped. The shape is preserved exactly.

Is there a file size limit?

No hard cap — the practical limit is your browser's memory. Typical print models convert instantly; very large scans (hundreds of MB) will be slow.

Which way does it convert?

Both. It reads the format from the file you drop: an STL comes back as OBJ, an OBJ comes back as STL.