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3DAI
Free · runs in your browser · no signup

Convert STEP to OBJ in Your Browser

STEP (.step or .stp) stores exact CAD solids, which Blender, game engines, renderers and most 3D apps cannot open. They want a triangle mesh such as OBJ. This page runs the open-source Open CASCADE kernel in your browser to tessellate every part, then writes an OBJ with one named object per part and an MTL with the part colours.

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How to use it

  1. 1

    Add your STEP file

    Drop a .step or .stp on the box or click to pick it. The CAD kernel (about 3 MB) downloads the first time you use the page.

  2. 2

    Choose quality and unit

    Standard suits most uses; Fine or Very fine give smoother curves for close-up renders. The unit sets what one OBJ unit means.

  3. 3

    Check the preview

    The model is shown as it goes into the OBJ, rotated Y-up for Blender and engines. Untick the rotation to keep the CAD Z-up axis.

  4. 4

    Download

    Get a ZIP with the OBJ and an MTL holding the part colours, or the OBJ alone.

What to know before you convert

  • STEP AP203, AP214 and AP242 solid and surface geometry is supported. Sketches, drawings, PMI annotations and assembly constraints are ignored.
  • OBJ stores a triangle mesh, so the exact curved surfaces become flat facets. The quality setting controls how fine they are.
  • Each STEP part becomes its own OBJ object with its name. Part colours go into the MTL when the STEP file has them; textures and CAD appearances do not exist in STEP.
  • Files up to 50 MB are accepted, and a conversion that would produce more than 4 million triangles is stopped with a message to use a coarser quality.
  • IGES, Parasolid (.x_t), SolidWorks and native CAD files are not supported. Export STEP from your CAD program first.

Don't have a model?

Create one with AI from a photo, a sentence or a sketch. The generators use credits; this converter is free and stays in your browser.

Image to 3D →Turn one photo into a textured 3D model.Text to 3D →Describe an object and get a GLB.Sketch to STL →Draw it, get a printable model.

Frequently Asked Questions

Drop the file above. The page loads the Open CASCADE geometry kernel as WebAssembly, turns the faces of every solid into triangles and writes them as an OBJ, all inside your browser tab.
Yes, as far as OBJ allows. Every part of the assembly becomes a separate named object in the OBJ, in its assembled position. When the STEP file stores colours, the MTL file gets one material per colour and each part uses its own.
OBJ has no unit field, so the numbers are what matters. Blender treats one unit as one metre, so pick Metres there to get real size. Most other tools and slicers expect millimetres, the default.
Curved CAD surfaces have to be approximated by flat triangles. Convert again with Fine or Very fine for smoother curves; the OBJ gets larger.
For 3D printing, yes: slicers expect STL. For Blender, rendering, games and AR, OBJ is the better pick because it keeps the parts separate and carries their colours.
No. The STEP file is read and converted inside your browser with the open-source Open CASCADE kernel compiled to WebAssembly. Nothing is sent to our servers, there is no account, and no credits are used.