OBJ to STL API

Turn OBJ models into the format every slicer and 3D printer accepts.

OBJ is the lingua franca of 3D content — it comes out of Blender, photogrammetry pipelines, scanners and asset stores, and it carries materials and texture coordinates alongside the geometry. Slicers do not want any of that. They want triangles, which is exactly what STL is. This endpoint strips the model down to printable geometry.

Example

curl -X POST "https://apimycad.com/v1/mesh?to=stl" \
  -H "X-API-Key: YOUR_KEY" \
  -F "file=@model.obj" \
  -o model.stl

Output is binary STL — far smaller than ASCII and read by every slicer.

What is kept, and what is not

Kept	All triangulated surface geometry, vertex positions, the shape itself
Dropped	Materials, textures, UV coordinates, colours, object names, scene structure

That is not a limitation of the conversion — STL simply has no place to store any of it. If you need appearance preserved, convert to GLB instead; if you are printing, none of it matters.

Two things that catch people out

• The .mtl file. OBJ stores materials in a companion .mtl file. You do not need it here — we are discarding materials anyway — so a "missing .mtl" warning is harmless for this conversion.
• Units and scale. Neither OBJ nor STL records a unit. A model that appears as 25 units wide might be intended as 25 mm or 25 cm. Conversion preserves the numbers exactly; check the scale in your slicer before printing.

Common uses

• Print-on-demand and instant-quote platforms that accept model uploads in any format
• Normalising scanned or sculpted models into a printable pipeline
• Converting a downloaded asset library into slicer-ready files in batch

Related conversions

STL to OBJ API OBJ to GLB API STL to GLB API All conversions

Read the API documentation