What is the PAR file format?
A .par file is a Solid Edge Part - a proprietary 3D CAD geometry file created by Solid Edge, the mechanical design software developed by Siemens Digital Industries Software (originally launched by Intergraph around 1996).
Each .par file stores a single mechanical component: its 3D solid geometry, parametric feature tree (extrudes, cuts, fillets and similar operations), sketch dimensions, constraints, and optionally material and physical properties. Parts are combined into products using .asm assembly files and documented with .dft drawing files. Sheet metal components use the related .psm extension.
The format is proprietary binary with no public specification. Its internal structure has changed across Solid Edge releases - older versions packaged parts inside an OLE/JET compound document container, while current releases use Siemens' own binary layout. No stable magic byte sequence exists, so .par files are best identified by project context.
Solid Edge incorporates synchronous technology, a hybrid modeling approach that pairs parametric history-based design with direct face editing inside the same file.
To exchange geometry with other CAD tools, engineers export to neutral formats such as STEP or IGES. The free Solid Edge Viewer can open .par files on Windows without a paid seat license.
Security & safety
RISK: LOWA Solid Edge .par is passive CAD geometry - it doesn't execute code, so it's safe to open in a viewer or CAD tool. The real cautions are non-malware: parts are intellectual property, so treat a received .par as confidential; a part saved in a newer Solid Edge may not open in an older version; and a STEP/IGES export drops the editable feature history (you get the solid, not the build steps). Avoid sketchy 'PAR opener/converter' sites that bundle adware - use the official Solid Edge Viewer or a reputable CAD converter.
Format details
in a nutshell- Parchive parity volume (PAR1) - Data-recovery file (starts 'PAR\0', successor .par2) that verifies and repairs split RAR/Usenet downloads; fed to a PAR tool like MultiPar, never 'opened'.
Programs that open PAR files
Windows3 apps
Solid Edge
Paid Native CAD editor - open and edit the .par part and its feature tree, and export to STEP/IGES. 
Solid Edge Viewer
Free Free official viewer - open the .par to view, rotate and measure the 3D part without a Solid Edge license.
CAD Exchanger
Freemium Open a Solid Edge .par to view it and convert to STEP/IGES/other CAD formats. Useful when you don't have Solid Edge. 
macOS1 app
CAD Exchanger
Freemium View the .par and convert it to a neutral CAD format on Mac (Solid Edge itself is Windows-only).
CAD Exchanger Online / web CAD viewers
Free Upload a .par to an online CAD viewer to inspect the 3D part in a browser without installing software. Technical details
deep spec| Developer | Siemens Digital Industries Software |
| Format type | Proprietary binary 3D solid CAD part |
| CAD geometry kernel | Parasolid (owned and embedded by Siemens) |
| Internal container (legacy versions) | OLE/JET compound document (similar to Access .mdb) |
| Internal container (current versions) | Siemens proprietary binary layout |
| Modeling paradigm | Synchronous technology - parametric history-tree and direct face-editing in one file |
| Stored data | Solid geometry, feature tree, sketch dimensions, constraints, material and physical properties |
| Companion formats | .asm (assembly), .dft (drawing), .psm (sheet metal part) |
| Magic bytes | None publicly defined; signature varies across Solid Edge versions |
| MIME type | application/octet-stream |
| Operating system | Windows (Solid Edge is a Windows-only application) |
| Neutral export formats | STEP, IGES, Parasolid (.x_t), JT, SAT/ACIS |
| Free viewer | Solid Edge Viewer for Windows (no license required) |
| Third-party converters | CAD Exchanger, TransMagic, Datakit CrossManager |
| Released | Solid Edge ~1996 (Intergraph; now Siemens) |
| Specification | docs.fileformat.com |
PAR conversions
Community Q&A
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