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3DAI
Free · runs in your browser · no signup

STEP Viewer: Open .step and .stp Files Online

Someone sent you a .step or .stp file and you do not have CAD software installed? Drop it here. The page runs the open-source Open CASCADE geometry kernel in your browser, so you can turn the model around, check its size in millimetres, list its parts with their colours and look at the mesh in wireframe, without uploading the file anywhere.

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How to use it

  1. 1

    Open the 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

    Look around

    Drag to orbit, scroll to zoom, right-drag to pan. Front, side and top buttons line the camera up; Wireframe shows the triangles.

  3. 3

    Check parts and sizes

    The panel lists every part with its colour, size and triangle count. Click a part to see it on its own and read its dimensions.

  4. 4

    Need a mesh?

    When the model looks right, convert it with STEP to STL for printing or STEP to OBJ for Blender and other 3D apps.

What to know before you convert

  • The viewer shows the solids and surfaces of STEP AP203, AP214 and AP242 files. Sketches, drawings, PMI annotations and assembly constraints are not shown.
  • Curved faces are drawn as fine triangles. The quality setting controls how fine; the size readout always comes from the real geometry.
  • Part colours are shown when the STEP file stores them. Parts without a colour are drawn light grey.
  • Files up to 50 MB are accepted. A model that would need more than 4 million triangles is stopped with a message to pick a coarser quality.
  • IGES, Parasolid (.x_t), SolidWorks, Inventor and other native CAD files are not supported. Export STEP from your CAD program first.

What Is a STEP File?

STEP (ISO 10303, saved as .step or .stp) is the neutral format CAD programs use to swap exact 3D models. SolidWorks, Fusion, Inventor, Creo, CATIA, Onshape and FreeCAD all export it. Unlike an STL mesh, a STEP file stores true curves and solid bodies, which is why engineers send STEP when a part has to be machined, printed or built into another design.

That also means you need a CAD kernel to open it. Most general 3D apps and image viewers cannot read STEP at all. This viewer brings the kernel to your browser, so a supplier drawing, a part from a manufacturer's website or a model from a colleague opens in a few seconds.

Other Ways to Open a STEP File

On Windows, the built-in 3D Viewer opens STL, OBJ, GLB, FBX, PLY and 3MF files, but not STEP. On a Mac, Preview and Quick Look do not open STEP either. If you want a desktop program, FreeCAD is free and open source and opens STEP on Windows, macOS and Linux, but it is a full CAD suite to install and learn.

On an iPhone, iPad or Android phone there is no built-in STEP viewer. This page works in a mobile browser for small and medium files. Large assemblies need more memory than most phones give a browser tab, so open those on a computer.

Many online CAD viewers upload your file to their servers first. This one reads it on your own device, which matters when the file is a client's design or under NDA.

After You Have Looked at the Model

To 3D print the part, convert it with STEP to STL. For Blender, game engines or a web page, use STEP to OBJ or STEP to GLB. Got an STL mesh instead? Open it in the STL Viewer, or turn it into a CAD file with STL to STEP.

Don't have a model?

Generate one from a sketch, image or text. Our AI generators give you a 3D model with an STL download for printing. They use credits; this converter does not.

Sketch to STL →Draw it, get a printable model.Image to STL →One photo of an object.Text to STL →Describe it in a sentence.

Frequently Asked Questions

Drop it on the viewer above. The page loads the Open CASCADE kernel as WebAssembly, reads the solids and draws them in 3D, all inside your browser tab. There is nothing to install and no account.
Nothing. .step and .stp are two extensions for the same ISO 10303 exchange format, and the viewer opens both.
The info panel shows the overall width, depth and height, the surface area and, for closed solids, the volume. Click a part in the list to read the same numbers for that part alone. Pick millimetres, centimetres, metres or inches; the file's own unit is converted for you.
The viewer shows what the STEP file contains. Some CAD programs export an assembly as one merged body, and many leave out colours. Re-export with the options for separate bodies and colours (often called AP214 or AP242) to keep them.
Yes. STEP to STL gives you a printable mesh for slicers, and STEP to OBJ gives you a mesh with one object per part and the part colours for 3D apps. Both run in your browser like this viewer.
Open this page in Safari or Chrome and drop the file on the viewer. macOS Preview and Quick Look do not read STEP, and iOS has no STEP viewer, but the browser can run the CAD kernel. On a phone, keep to small and medium files; big assemblies need a computer.
Yes. There is no account, no watermark and no limit on how many files you open. The only limit is size: files up to 50 MB, which covers almost every part and most assemblies.
No. The STEP file is read 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.