Free STEP (.step, .stp) to 3MF (.3mf) 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 · LAS · PCD · XYZ · PTS
STEP is the industry-standard exchange format for parametric CAD data. It stores exact boundary-representation (B-rep) geometry — true curves and surfaces rather than triangles — which makes it the preferred way to move solid models between CAD systems like SolidWorks, Fusion 360, Inventor, CATIA and NX without losing precision.
3MF is the modern replacement for STL, backed by the 3MF Consortium (Microsoft, HP, Autodesk, Prusa and others). It stores watertight meshes together with units, colors, materials and print settings in one ZIP-based file, and current slicers increasingly prefer it over STL.
| STEP | 3MF | |
|---|---|---|
| Geometry | Exact B-rep solids & surfaces | Watertight triangle mesh |
| Units | Yes, embedded | Yes, required by spec |
| Colors & materials | Per-part colors | Colors & materials |
| Animations | No | No |
| Typical use | CAD exchange between engineering tools | Modern 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 .step file never leaves your device, which makes it safe for confidential designs.
STEP stores exact CAD surfaces, which are tessellated into triangles at a quality you choose — from fast drafts to near-exact precision meshes. Preview the result in the built-in 3D viewer before downloading.
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.
STEP stores exact boundary surfaces, but every output available here is a triangle mesh. Tessellation is irreversible: feature history, constraints and analytic curves cannot be recovered from the converted file. The 3MF writer keeps model units, part names and one base color per mesh, but it does not write textures, advanced materials or print settings.
You received a .step or .stp file but have no CAD program installed. Here are your options — including a free browser-based STEP viewer that needs no install.
What do tessellation quality settings actually control? Linear and angular deflection explained with practical presets for 3D printing, rendering and web delivery.
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.