What is the SLDPRT file format?
A .sldprt file contains the 3D drawing of an element that is a part of a larger project of a device or construction. Stored in a proprietary binary format native to SOLIDWORKS software (developed by Dassault Systèmes), the file uses an OLE2 Compound File Binary container with geometry data encoded via the Parasolid kernel. The software allows users to design assembly models, save technical drawings, and create simulations or animations. Each new SOLIDWORKS CAD release offers new features and additional functions, so .sldprt files created using later versions may not be fully backward-compatible with older installations.
SOLIDWORKS uses the following formats to save project data:
.sldprt- part file (this format),- .sldasm - assembly file that can be composed of many
.sldprtparts, - .slddrw - SOLIDWORKS engineering drawing file.
Each of these formats is a container file that stores various project data streams, including a preview image (JPEG thumbnail), feature tree, and metadata. The full parametric feature history is preserved in .sldprt, meaning dimensions, constraints, and modeling operations remain editable - not just the resulting mesh.
.sldprt files can be viewed using dedicated project viewer tools such as eDrawings. Many CAD applications allow users to import .sldprt data and convert it to their native format - for example to .step or .stl. However, such conversion is not always possible without some data loss, as the parametric feature tree typically collapses to a static solid on export.
SOLIDWORKS projects integrate very well with other types of CAM (Computer Aided Manufacturing) software tools. .sldprt files are also a practical data-exchange format, as they allow users to share relevant parts of their projects without the need to disclose the whole project stored in an .sldasm file. SOLIDWORKS has been on the market since 1995 and competes with other professional CAD tools. New versions are released each year, available as Standard, Professional, Premium, Education, or Simulation packages.
Security & safety
RISK: LOWSLDPRT is a passive CAD data file - it contains geometry and metadata, not executable code, so opening one in a viewer is safe. The practical cautions are non-malware: a part saved in a newer SOLIDWORKS version may not open in an older one, and exporting to mesh formats (STL/OBJ) discards the editable feature history. Treat shared parts as intellectual property. Only the usual advice applies: get files from sources you trust.
Format details
in a nutshellPrograms that open SLDPRT files
Windows3 apps
SolidWorks
Paid The native editor. File > Open the .sldprt to view and fully edit the part and its feature tree. 
eDrawings Viewer
Free Free official Dassault viewer. Open the .sldprt to view, rotate, measure and print - no SOLIDWORKS needed. 
Autodesk Fusion 360
Freemium Upload/insert the .sldprt; Fusion imports SOLIDWORKS parts directly for editing or export. 
macOS2 apps
eDrawings Viewer
Free Free Dassault viewer for Mac; open the .sldprt to view/measure (SOLIDWORKS itself is Windows-only).
Autodesk Fusion 360
Freemium Mac CAD app that imports SOLIDWORKS parts; insert the .sldprt to view, edit and re-export. 
Android1 app
SOLIDWORKS 3D viewer (3DEXPERIENCE) / Sibe.io
Free Upload the .sldprt to a browser viewer to rotate, measure and inspect without installing anything.
GrabCAD / online STEP viewers
Free Free in-browser viewing of CAD parts; useful for a quick look or sharing a review link. Technical details
deep spec| Container format | OLE2 Compound File Binary (Microsoft CFB) - the same low-level container used by legacy .doc and .xls files |
| File header | Starts with OLE2 magic bytes D0 CF 11 E0 A1 B1 1A E1 at byte offset 0; SOLIDWORKS-specific data is held in named internal sub-streams |
| Geometry kernel | Parasolid (Siemens) - boundary representation (B-rep) solid modeling |
| Modeling paradigm | Parametric, feature-based; the full feature history (feature tree) is stored and remains editable in SOLIDWORKS |
| MIME type | application/octet-stream |
| Embedded thumbnail | JPEG preview image stored as an internal OLE2 data stream, visible in Windows Explorer without opening SOLIDWORKS |
| Configuration support | A single .sldprt file can contain multiple named design configurations representing size or shape variants of the same part |
| Physical properties | Material, density, mass, center of mass, and moment of inertia can be stored and auto-calculated per part |
| Version locking | File format is tied to the SOLIDWORKS release year; parts saved in a newer version cannot be opened in an older installation without conversion |
| Simulation data | SOLIDWORKS Simulation (FEA) mesh, boundary conditions, and results can be embedded directly in the .sldprt file |
| Export targets | STEP (.step/.stp), IGES (.igs), STL (.stl), Parasolid (.x_t), DXF, and ACIS (.sat) |
| Format disambiguation | Cannot be identified by magic bytes alone - the OLE2 header is shared with .sldasm, .slddrw, .doc, and .xls; the .sldprt extension and internal OLE2 stream names are required |
| Appearance data | Supports per-body and per-face materials, colors, decals, and RealView optical textures |
| Design table | An embedded Microsoft Excel spreadsheet (design table) can drive part configurations and parametric dimensions |
| Released | 1995 (SOLIDWORKS 95) |
| Specification | www.solidworks.com |
SLDPRT conversions
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