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Updated: April 07, 2025

.STEP File Extension

There is only one filetype that uses .STEP file extension and it is STEP 3D Model.

STEP 3D Model

File category: CAD Files
Developer: International Organization for Standardization (ISO)
Open with: Autodesk Fusion 360 (+7 more)
Platforms: Windows, macOS, Linux

A STEP file is a standardized 3D model file format used for exchanging product design data between different Computer-Aided Design (CAD) systems. The name STEP stands for "Standard for the Exchange of Product Data". Despite appearing as complex 3D models when opened in CAD software, STEP files are actually plain text files containing ASCII code that describes the model's structure according to specific ISO standards.

Files in this format typically use either the .STEP or .STP extension.

The STEP format was developed by the International Organization for Standardization (ISO) and was officially released in 1994. It was specifically created to solve compatibility issues in the CAD industry, allowing users with different CAD systems to easily share and transfer 3D models without data loss or conversion problems.

STEP files conform to the ISO 10303 standard, also known as "STEP Application Protocols". The text within these files follows a structured format that defines the geometric and topological elements of the 3D model, along with metadata about the file's creation.

STEP files are primarily used for:

  • Transferring 3D models between different CAD programs
  • Preserving design intent when sharing files across design teams
  • Long-term archiving of product design data
  • Manufacturing processes where precise model data is required
  • Compatibility with various engineering and design workflows

How to Open .STEP as STEP 3D Model

STEP files can be opened with various CAD applications:

Popular CAD Software That Supports STEP Files:

  • Autodesk Fusion 360 (Windows, Mac, browser-based)
  • IMSI TurboCAD (Windows, Mac)
  • FreeCAD (Windows, Mac, Linux)
  • Dassault Systemes CATIA (Windows, Linux)
  • SolidWorks (Windows)
  • Onshape (browser-based)
  • Rhino 3D (Windows, Mac)

Opening a STEP File in Autodesk Fusion 360:

  1. Select File → Open from the menu bar
  2. Choose "Open from my computer"
  3. Navigate to and select your STEP file
  4. Click Open

Viewing STEP Files Without CAD Software

Since STEP files are stored in plain text format, you can open them with any text editor like Notepad (Windows) or TextEdit (Mac) to view the underlying data and metadata. This can include information such as:

  • Original file name
  • Creation date
  • Application that created the file
  • Model structure and geometric data

While text editors allow you to modify the file, it's not recommended unless you understand the STEP file structure, as incorrect edits can corrupt the file.

How to Convert an STEP File

STEP files can be converted to various other 3D and 2D formats using most major CAD applications.

Common Conversion Options:

  • .STL files (for 3D printing)
  • .OBJ files (for rendering and visualization)
  • .IGES files (another CAD exchange format)
  • .DWG or .DXF files (for 2D drawings)
  • .3MF files (for advanced 3D printing)

Converting in Fusion 360:

  1. Open the STEP file in Fusion 360
  2. Select File → Export
  3. Choose your desired output format
  4. Configure any format-specific options
  5. Select the save location and click Export

Online Conversion Options:

Several online services also allow STEP file conversion without installing CAD software:

  • OnShape (browser-based CAD with conversion features)
  • Various online conversion tools (though quality may vary)

Applications That Open STEP Files

Windows Apps for STEP Files:

macOS Apps for STEP Files:

Linux Apps for STEP Files:

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