CAD (computer-aided design) files are digital files that house 3D & 2D designs as well as information regarding materials, processes, tolerances, and other data.

From design to production, everything begins with the CAD file.

However, think of the various stakeholders that eventually handle the file:

  • Different companies
  • Internal departments
  • Employees
  • Suppliers
  • Sub-contractors
  • Customers

All use different CAD software, making interchange difficult for all– especially when geometric information and 3D annotations such as PMI (product manufacturing information) must maintain integrity.

Native CAD file formats from PTC Creo, Siemens NX, CATIA, SolidWorks, Autodesk Inventor, and others are proprietary and need to be translated & validated for downstream processing.


Neutral CAD file formats, however, are interoperable between different CAD software. Today we look at the best 8 neutral CAD file formats, especially pertaining to mechanical CAD conversion. 

Capvidia is a firm believer in CAD formats that are standards (e.g. ISO, ANSI, etc. that ensure quality and consistency) and that are model-based definition (MBD) ready.

MBD CAD files include both the geometry and product manufacturing & quality requirements, which are normally done on 2D drawings. 

By combining 2D drawing information into the 3D CAD model, it becomes the authoritative source for a product's lifecycle. This enables automation, data insights, and connectivity from design to manufacturing from a single source of truth that is both human and machine readable.

It's CAD in the age of IoT connectivity and smart data.

Have Questions About Neutral CAD Files?

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Capvidia is a leader in CAD translation & validation, especially pertaining to digital transformation and the MBD journey. Have questions? Talk to our team today.

Table of Contents:

MBD CAD Files:

  1. STEP
  2. QIF
  3. JT

Non-MBD CAD Files:

  1. 3D PDF
  2. IGES
  3. STL
  4. ACIS

1. STEP (File Extension: *.STEP, *.STP)

  • Year Introduced: 1994, Last Update: 2020.
  • Standard: ISO 10303-242:2020
  • Representation: B-rep (precise) & Vis-rep (approximation)
  • Organization: International Organization for Standardization and PDES Inc.

STEP files are the most widely used & accepted neutral CAD format today, therefore, making it a standard across multiple industries.

Most CAD software supports importing & exporting STEP files, allowing it to be interoperable between different systems including CAM (computer-aided manufacturing), CAI (computer-aided inspection), and CAE (computer-aided engineering). 

In regards to mechanical CAD there are three major STEP file formats:

  1. STEP AP203: Defines geometry, topology, and configuration management data of solid models for mechanical parts & assemblies. 
  2. STEP AP214: Includes STEP AP203 features along with colors, layers, GD&T, and design intent.
  3. STEP AP242: Merges both STEP 203 & STEP 214 to introduce model-based definition (MBD) workflows.

However, both STEP AP203 and STEP AP214 have deprecated in favor of STEP AP242.


  • Mature and ubiquitous file format.
  • MBD-ready if using AP242.


  • Big organization means slow to release new updates quickly. 

2. QIF (File Extension: *.QIF)


  • Year Introduced: 2013, Last Updated: 2020
  • Standard: ISO 23952:2020
  • Representation: B-rep (precise) & Vis-rep (approximation)
  • Organization: DMSC (Digital Metrology Standards Consortium)

QIF (Quality Information Framework) files are made for the  digital manufacturing in the 21st century. It optimizes for semantic PMI which allows for human & machine-readable CAD leading to two main things: interoperability & traceability downstream.

Although the newest format on this list, its gained the more attention as more OEMs need a robust file format to exchange data downstream from design to manufacturing to quality.


  • Most robust neutral MBD CAD file.
  • XML-based framework: easy integration & interoperability with other systems, web/internet applications, and other formal standards. 
  • Highly valued in Metrology and Quality departments.


  • Although gaining credibility in MBD, still early and has not gained widespread adoption. Learn more about QIF.

3. JT (File Extension: *.JT)

  • Year Introduced: 2007, Last Updated: 2017
  • Standard: ISO 14306:2017
  • Representation: B-rep (precise) & Vis-rep (approximation)
  • Organization: Siemens PLM Software

JT (Jupiter Tessellation) files are the most confusing of the neutral CAD format group. Although known for vis-rep, it can also have full B-rep and PMI, therefore making it MBD-ready.

It's internal B-rep representation is flexible, including support for ISO 10303 (STEP) and Parasolid. If a JT exported from NX contains B-rep data, it will be in the Parasolid format.

Although JT is technically an open format,  many vendors utilize Siemen's JT Open Toolkit. This toolkit is particularly important if dealing with Parasolid data, which makes use of blends with proprietary recipes. Because of this, it isn't quite widely accepted as STEP or QIF.


  • Common interoperability format for Siemens users.
  • JT is primarily used in automotive industry.
  • Lightweight format.


  • Less common outside of Siemens software environments.

4. 3D PDF (File Extension: *.PDF) 


  • Year Introduced: 2004, Last Updated: 2014 (for CAD)
  • Standard: ISO 14739-1:2014
  • Representation: Vis-rep (approximation)
  • Organization: 3D PDF Consortium 

3D PDF files are popular for a reason. It’s a ubiquitous format, easily viewed on computers, smartphones, and tablets. Especially convenient for those who don’t have CAD systems or viewers.


  • Only requires Adobe Reader to view files.
  • PDF files can be used as containers for other files like STEP, QIF, or other documentation.


  • Huge file size and slow performance.
  • 3D ergonomics in Adobe aren’t great.
  • What this file type is capable of doing is sharply limited by the Adobe environment.

5. Stereolithography Files (File Extension: *.STL)

  • Year Introduced: 1987, Last Updated: None.
  • Standard: None.
  • Representation: Vis-rep (approximation)
  • Organization: 3D Systems

STL files are universal 3D formats that focuses on surface geometry and shapes but not for colors, textures, or other model attributes, which is good for rapid prototyping, 3D printing, and some CAM software.

However, it uses triangulated mesh surface which is acceptable for visual representation, but not workable in CAD systems since most work in solids.

When complicated CAD is not required, STL files are acceptable in most basic situations.


  • Widely supported file format.
  • Popular for 3D printing.


  • Describes surface geometry only — it is not precise B-rep.
  • Very simple data model — no support for color, surface grouping, or even user-defined attributes.

6. IGES (File Extension: *.IGS, *.IGES)

  • Year Introduced: 1980, Last Updated: 1996
  • Standard: ANSI
  • Representation: B-rep (precise)
  • Organization: American National Standards Institute

IGES files were the first neutral CAD file invented and deployed in the late 1970s/early 1980s. 

Although an older standard technologically superseded by STEP & QIF, it’s still used today since it’s been around for a long time and is very widely supported.

Mostly used for surface geometry (although it can support solid models) and design work. Can often get translated with gaps between surfaces, missing faces, and even surfaces with wrong orientation. So it’s recommended to go with STEP or QIF or have a tool for repairing bad geometry and stitching surfaces.


  • It’s your grandfather’s CAD file.
  • Ubiquitously supported.


  • IGES can support solids, however, it's mostly used for surface geometry. 

7. ACIS (File Extension: *.SAT)

  • Year Introduced: 1989, Last Updated: 2019
  • Standard: None.
  • Representation: B-rep (precise) & Vis-rep (approximation)
  • Organization: Dassault Systemes

ACIS files are 3D solid and surface CAD files from Spatial, a Dassault Systemes division. It is a geometric modeling kernel compiled in C++ and used in CAD, CAM, CAE, and CMM. 


  • The internal modeling language used by many modeling software such as AutoCAD, BrisCAD, and Cimatron.


  • Not a standard data format.
  • Usually requires a custom translators to export to ACIS.
  • Doesn’t support semantic PMI in any standard way.

8. PARASOLID (File Extension: *.X_T)

  • Year Introduced: 1989, Last Updated: 2019
  • Standard: None.
  • Representation:  B-rep (precise)
  • Organization: Siemens 

Parasolid files are used by the geometric modeling kernel currently owned by Siemens and used in CAD, CAD exchange, CAM, CAE, and product visualization.

Licensed and used in over 350+ applications such as NX, SolidWorks, SolidEdge, MasterCAM, Onshape, and others.

Can represent wireframe, surface, solid, and general non-manifold models. Most Parasolid files migrate 3D solids and/or surface data. 


  • The internal modeling language used many CAD and downstream software.
  • Great CAD export option if you use NX or SolidWorks.


  • Not a standard data format.
  • Uses some proprietary blend recipes, making some data inaccessible to non-Parasolid modelers.

Have questions about neutral CAD formats? Ask away, we'll be happy to help.

Contact Us

Capvidia is a leader in CAD translation & validation, especially pertaining to digital transformation and the MBD journey. Have questions? Talk to the expects today.

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