STEP file viewer online — open .step & .stp with no upload
View STEP, STP and IGES files in your browser without CAD software or an account. Browse the assembly, isolate parts, measure distances and holes, cut cross-sections, and export a BOM or STL. Your file never leaves your device.
Measure
Click a part to isolate it and see its own dimensions.
Dimensions & mass
Load a model to see its dimensions, volume, surface area and mass.
Cross-section
Measuring tips
- Snap is on by default — clicks land on the nearest corner or edge vertex, which is where CAD tessellations keep exact dimensions.
- Hole diameters: click three points spread around the rim (not in a line). The fit is a true 3D circle, so it works on tilted faces too.
- Units: STEP/IGES are read in millimetres from the file. Mesh formats carry no units, so the tool applies each format’s convention — if a model looks 10×, 25×, or 1000× off, switch File units rather than the display unit.
- Mass multiplies the closed-mesh volume by the material density — pick the right material, and expect open or hollow meshes to read low.
- X-ray + cross-section together show internal pockets, wall thickness and hidden holes.
Capabilities
What the STEP viewer does
- Opens .step, .stp, .iges and .igs files with OpenCascade compiled to WebAssembly — real B-rep CAD geometry, tessellated finely, in any modern browser.
- Nothing is uploaded: the file is read on your device, so confidential customer or supplier CAD never leaves your machine. No account, no watermark.
- Assembly tree with part names and colours from the file — click a part to isolate it, or view the whole model with orbit, zoom, pan and X-ray shading.
- More than a viewer: point-to-point distances, angles, hole diameters, bounding box, volume, surface area and mass by material for the model or any part.
- Cross-section on any axis with the section outline and area, to check walls, pockets and internal features without opening a CAD seat.
- Export a parts list as a CSV bill of materials, download any single part as STL or GLB, or save an annotated screenshot for a quote or an email.
Process
How it works
- Drop the STEP fileDrag a .step or .stp (or .iges / .igs) onto the viewer. OpenCascade loads in WebAssembly and tessellates the solids locally — nothing is sent anywhere.
- Browse and inspectRotate, zoom and pan. Open the parts list to isolate components, read each part’s dimensions, volume and mass, or cut a cross-section to see inside.
- Measure and exportPick Distance, Angle or Hole ⌀ and click on the model, then export a BOM as CSV, download a part as STL/GLB, or save a screenshot with your dimensions.
No CAD licence needed
How to open a STEP file without SolidWorks, Fusion 360 or FreeCAD
You only need a browser. Drop the file here and it opens in seconds — no installation, no trial, no account. Suppliers and customers send STEP because every CAD system exports it, but reading it usually meant installing a viewer or uploading the file to someone’s server. This viewer runs OpenCascade, the same open-source CAD kernel behind FreeCAD, inside your browser tab, so you can check a part before quoting, verify a revision, or take dimensions from a drawing-less model without a CAD seat.
File formats
STEP vs STP vs IGES — what the extensions mean
.step and .stp are the same thing: ISO 10303 STEP files, the standard for exchanging solid models between CAD systems, with precise B-rep geometry, part names, colours and assembly structure. IGES (.iges / .igs) is the older exchange format; it often stores surfaces rather than sealed solids, so it opens fine for viewing but volume and mass can be meaningless. Need a mesh for 3D printing or the web instead? Convert with the STEP to STL or STEP to GLB tools, or download a single part from the parts list here.
Notes
Good to know
- The viewer shows tessellated geometry (fine deflection) and the assembly structure — not the feature tree, sketches, PMI or drawings stored in native CAD files.
- The in-browser OpenCascade engine handles files up to roughly 120 MB; very large assemblies may need a lighter export (fewer parts) from the sender.
- Part names and colours are read from the file; exporters that don’t write them show generic part labels and a neutral colour.
- Measurements are taken on the tessellated surface, accurate to a small fraction of a millimetre on curved faces rather than analytically exact.
FAQ
Questions, answered
Can I open a STEP file without CAD software?
Yes. This viewer reads STEP and STP files with OpenCascade compiled to WebAssembly, entirely in your browser — no SolidWorks, Fusion, Inventor or FreeCAD needed, and nothing to install.
Is my STEP file uploaded to a server?
No. The file is parsed and displayed on your own device. It is never uploaded, which is what makes it safe for confidential customer and supplier CAD.
Is .stp the same as .step?
Yes — both are ISO 10303 STEP files with different extensions. The viewer treats them identically, and also opens IGES (.iges / .igs).
Can I measure a STEP file in the viewer?
Yes. Switch to Distance, Angle or Hole ⌀ and click on the model; clicks snap to corners and edges. The panel also shows the bounding box, volume, surface area, centre of mass and mass by material for the whole model or a selected part.
How do I convert a STEP file to STL?
Select a part in the parts list and download it as STL (or GLB) straight from the viewer, or use the STEP to STL converter for the whole model with a choice of mesh quality.
Can I get a parts list or bill of materials from a STEP assembly?
Yes. Assemblies show every part with its name, dimensions, volume and mass; export the list as a CSV BOM for quoting, an RFQ or an ERP import.
What is the maximum file size?
About 120 MB for STEP and IGES — the limit of the in-browser CAD kernel’s memory. Most single parts and small assemblies are well under that.
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