Convert PAR to CATPart in your application
3D InterOp is a CAD interoperability SDK that lets your software read PAR files and write CATPart, with exact B-Rep geometry carried across and nothing tessellated.
Spatial does not offer an online converter or a desktop conversion app. 3D InterOp is a component that software vendors embed in their own products.
- Reads Solid Edge part · Writes CATPart
- Exact geometry → exact geometry
- C++ / C# APIs
PAR to CATPart at a glance
Both formats store exact geometry, so the model stays exact. The differences are in the product data each one can carry.
| Solid Edge part (source) | CATPart (target) | |
|---|---|---|
| Full name | Solid Edge Part | CATIA V5 Part |
| Standard / owner | Siemens | Dassault Systèmes |
| File extensions | .par | .CATPart |
| Geometry | Exact B-Rep | Exact B-Rep |
| Assemblies / structure | Part file | Part file (assemblies are CATProduct files) |
| PMI | Not imported by 3D InterOp | Semantic and graphical |
| 3D InterOp support | Read only | Read and write |
What's preserved, what changes
Here is what your application can expect to carry across from Solid Edge part to CATPart.
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Preserved
Exact geometrySolids and surfaces stay exact B-Rep. The model is never reduced to a triangle mesh.
Why software vendors add PAR to CATPart conversion
Deliver in your customer’s CAD format
Aerospace and automotive OEMs often require supplier data in CATPart. Writing it lets your users meet that requirement directly from your application.
Exact geometry, ready to edit
CATPart keeps exact B-Rep geometry, so the receiving engineer can measure, modify or machine the model in CATIA.
No neutral-format round trip
Writing CATPart directly avoids an extra STEP or IGES step, and the loss each extra translation can add.
Things to check before you ship
- Written CATPart versions: CATIA V5 R15 to V5-6 R2026.
- Supported PAR input: Solid Edge V18 to SE 2026.
- Validate a sample of translated files in the target system your users actually work with.
Working with Spatial was a real milestone for us: Thanks to the powerful 3DInterOp library, we were able to successfully bring our complex CAD-based solutions to the cloud while remaining flexible to meet individual customer requirements. For us, Spatial is not just a technology partner, but a true enabler of our product strategy.
Dr. Arno Michelis, Founder, Simus Systems
Read the Case StudyAbout the formats
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Source format
What is a PAR (.par) file?
A PAR file is a Siemens Solid Edge part. Solid Edge is built on the Parasolid kernel and stores sheet metal parts in PSM files and assemblies in ASM files.
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Target format
What is a CATPart (.CATPart) file?
A CATPart file is a CATIA V5 part: one component with its exact 3D geometry, features and, often, PMI. Assemblies of parts are stored in CATProduct files.
Frequently asked questions
Yes. Both formats store exact B-Rep geometry, so the model is translated without being tessellated into triangles.
Yes. If your application uses Parasolid, a Parasolid-based Solid Edge reader is available.
3D InterOp reads Solid Edge V18 to SE 2026.
3D InterOp writes CATIA V5 R15 to V5-6 R2026.
No. 3D InterOp reads PAR but doesn’t write it. To send data back to Solid Edge users, write a neutral format they can import, such as STEP.
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Building software that needs to convert PAR to CATPart?
3D InterOp is an SDK that lets your application read Solid Edge part and write CATPart alongside 30+ CAD and BIM formats.