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STEP file format (.step, .stp)

STEP (ISO 10303, Standard for the Exchange of Product model data)

What is a STEP file?

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.

  • Exact B-rep solids — no loss of precision
  • Preserves assembly structure and part names
  • Supported by virtually every professional CAD package
  • ISO-standardized and vendor-neutral

Best for: Exchanging precise mechanical parts and assemblies between CAD systems.

View STEP files online

Open .step / .stp files in the free online STEP viewer — assembly tree, section views and display modes, entirely in your browser.

How to open a STEP file

  1. Open the online STEP viewer. It runs in your browser, so there is no software to install and no account to create.
  2. Drop your .step or .stp file in. The file is parsed locally and never uploaded. Inspect it with the assembly tree, section views and display modes.
  3. Convert it if you need another format. Press Convert to turn STEP into STL, then download the result straight from your browser.

Convert STEP to other formats

STEP to STLSTEP to OBJSTEP to PLYSTEP to GLBSTEP to glTFSTEP to 3MFSTEP to OFFSTEP to USDZ

Frequently asked questions

How do I open a .step file?

Drop it into the free online STEP viewer on this site — it renders in your browser with an assembly tree and section views, and the file is never uploaded. No software install needed.

Does STEP store units and colors?

Units: yes, embedded. Colors/materials: per-part colors. Geometry is stored as exact b-rep solids & surfaces.

How do I convert STEP to STL?

Use the free STEP to STL converter: drop the file, press Convert, download. Everything runs locally in your browser — no upload, no signup.

What is STEP best used for?

Exchanging precise mechanical parts and assemblies between CAD systems.

Does STEP preserve the original feature history?

No. STEP preserves exact exchanged geometry and can carry assemblies and part colors, but sketches, constraints, parameters and the native CAD feature tree are not recoverable from it.

Can STEP store animation?

No. STEP is used for cad exchange between engineering tools, and its format does not carry animation tracks.