3D File Converter
Convert between STL, 3MF, STEP/STP and OBJ – right in your browser, no upload, no sign-up.
How the converter works
Choose a file, pick the target format, click “Convert” and download. Everything happens in your browser – the file is not uploaded.
STL ↔ 3MF ↔ OBJ are triangle meshes. The pure geometry is kept when converting; colours, textures, materials and slicer settings may be lost (see the questions below). 3MF is the more modern format: it stores units properly and is read directly by Bambu Studio, PrusaSlicer, OrcaSlicer and Cura.
STEP/STP → STL/3MF: STEP contains true CAD surfaces. On conversion a triangle mesh is computed; you set the detail level yourself. For this the page loads a module once (OpenCascade, about 3 MB).
STL/3MF → STEP: The original CAD surfaces cannot be recovered from a mesh. The converter does merge triangles that lie in one plane into a single flat face, though. For parts made of flat faces (plates, brackets, boxes) the result is a body you can keep editing at its edges and faces in CAD programs such as SolidCraft, FreeCAD or Fusion. Round shapes stay many small flat faces. For figures, scans and very large meshes (over 400,000 triangles) the converter does not offer STEP, because the file would be huge and unusable. Use STL or 3MF for those.
Frequently asked questions
Is my file uploaded?
No. The conversion runs entirely locally in your browser. No data is sent to a server.
What is the difference between STL and 3MF?
STL stores only triangles without a unit. 3MF is a modern package with units and can hold additional data. The geometry stays the same on conversion.
Why is my STEP file so large after STL/3MF → STEP?
Every triangle becomes its own face. Models with very many triangles therefore produce large STEP files. Reduce the triangle count beforehand if needed.
Are colours or multiple parts lost?
The converter transfers geometry. Colours, textures and slicer settings from 3MF project files are not carried over.
STEP processing uses occt-import-js (OpenCascade Technology, LGPL 2.1).
More tools: Slicer Settings Helper, Remaining Filament Calculator, Cost Calculator.