The 3D File Converter That Shows Its Work

Convert between STL, STEP, 3MF, OBJ, PLY and GLB — or repair a broken mesh — with a real geometry engine, not a black box. Every job returns quality metrics: faces, volume preserved, what was simplified. Free for everyday files.

STL ↔ STEP ↔ 3MF ↔ OBJ ↔ GLBQuality metrics on every jobFree ≤25 MB · 10/dayNo sign-up

All converters & tools

STL → STEPMesh to CAD solid — real BREP rebuildSTEP → STLCAD to printable mesh3MF → STLUnpack slicer project filesOBJ → STLModels to printable meshesSTL → OBJInto Blender/Maya/UnityPLY → STLScans to printable meshesGLB → STLAI/AR models to the printerSTL → GLBModels to web & ARImage → STLPictures to 3D reliefsRepair STLFix non-manifold meshes

Built on real geometry kernels

Under the hood: OpenCascade (the kernel inside FreeCAD and many commercial CAD tools) handles STEP; industrial-strength mesh processing handles everything else. STL→STEP uses coplanar-region BREP reconstruction with hole-loop recovery and closed-solid verification — then tells you the resulting face count and volume accuracy. High-poly meshes are auto-simplified with measured, near-lossless error (we benchmarked 0.01 mm max deviation on a 40 mm part) and full disclosure in the metrics.

Frequently asked questions

What file formats are supported?
Input: STL, OBJ, PLY, OFF, GLB/glTF, 3MF, DAE, STEP/STP, plus PNG/JPG images for relief generation. Output: STL, OBJ, PLY, OFF, GLB and STEP. The trickiest pair — STL to STEP — uses real BREP reconstruction with coplanar face merging.
Why show quality metrics?
Because 3D conversion silently degrades files everywhere else. We report input/output face counts, volume preservation, the reconstruction method used and any auto-simplification — engineers deserve to know exactly what happened to their geometry.
Is this converter free?
Yes — up to 10 conversions a day and files up to 25 MB, no account needed. Larger files (up to 60 MB) and high-detail STEP output use credits ($9 for 20). Everything runs server-side on real geometry kernels, and failed jobs auto-refund.
What happens to my files?
Files are uploaded only to run your conversion and stored briefly so you can download the result. We don't share them, mine them or train on them. See our privacy policy.