What is the SKF file format?
.skf files are associated with the AutoSketch software application by Autodesk. .skf files store CAD (Computer Aided-Design) drawing projects for AutoSketch - Autodesk's entry-level 2D drafting and illustration tool. Each .skf file holds a technical drawing represented as 2D vector geometry, along with an embedded thumbnail preview of that drawing. The format is proprietary and undocumented, recognized only by AutoSketch itself.
AutoSketch also supports more widely compatible formats such as .DWG, .DXF, and .SKD, which are better choices for long-term storage or interoperability with other CAD tools.
AutoSketch is no longer actively developed; as of October 26, 2016, it is officially discontinued. .skf files are rarely seen anymore. Although the tool never supported 3D graphics, it was popular for simple 2D technical drawings, floor plans, and illustrations.
Note that the .skf extension is also used by unrelated software - including SkinCrafter skin files and certain Sage accounting data files - so the extension alone does not identify AutoSketch content. If you still have a working AutoSketch installation, the recommended approach is to export .skf drawings as .dxf for use in modern CAD applications.
Security & safety
RISK: LOWAn AutoSketch .skf is inert drawing data and poses little direct risk - it isn't executed. The practical concerns are non-malicious: the format is obsolete, so you may struggle to open old files without AutoSketch, and you should export to DXF before the last working install disappears. Beware generic 'open any SKF file' download sites that bundle PUPs/adware; prefer AutoSketch, XnView, or a real CAD tool. Confirm an unidentified .skf isn't actually a SkinCrafter skin or Sage data before choosing a tool.
Format details
in a nutshell- SkinCrafter skin file (.skf) - SkinCrafter (a Windows GUI-skinning SDK) saves custom application skins as .skf - unrelated to CAD, opened in SkinCrafter.
- Sage accounting data (.skf) - Some older, discontinued versions of Sage accounting software stored data in .skf files.
Programs that open SKF files
Windows3 apps
AutoSketch / Autodesk
Paid Open the .skf in AutoSketch (if you still have a working install) - the only native reader. Immediately export to DXF to future-proof the drawing. Product is discontinued. 
XnView MP
Freemium Try opening the .skf to view its embedded thumbnail/preview. XnView reads many legacy formats but may only show the preview, not the editable vector data.
A CAD viewer (after DXF export)
Open-source Once the .skf is exported to DXF from AutoSketch, open the DXF in LibreCAD or any free CAD viewer/editor to view, measure and convert it. Technical details
deep spec| File type | Proprietary 2D vector drawing and embedded thumbnail file |
| Encoding | Binary, little-endian (Windows-native byte order) |
| File signature (magic bytes) | No published magic-byte signature; identified by file extension and AutoSketch association only |
| Embedded thumbnail | Contains an embedded preview thumbnail of the drawing, reflected in the file's full name "AutoSketch Thumbnail File" |
| Geometry support | 2D vector objects: lines, arcs, polylines, splines, text, and dimensions |
| Layer support | Supports named drawing layers, consistent with AutoSketch's layer-based 2D drafting model |
| 3D geometry | Not supported; AutoSketch is strictly a 2D drafting and illustration tool |
| MIME type | application/octet-stream (no dedicated registered MIME type) |
| Associated operating system | Windows only |
| Typical file size | Tens of KB to a few MB depending on drawing complexity |
| Format versioning | Version is tied to the AutoSketch release that wrote the file; files created in later versions may not open in earlier builds |
| Third-party compatibility | No documented third-party reader support; AutoSketch is the only application that can reliably open .skf files |
| Extension name collision | The .skf extension is also claimed by SkinCrafter skin files and legacy Sage accounting data - context and source determine actual file type |
| Product status | AutoSketch product line officially discontinued by Autodesk on October 26, 2016; no further updates or support |
| Migration recommendation | Export to .dxf while a working AutoSketch installation is available; .dxf is widely supported by modern CAD applications |
| Related formats | .dwg and .dxf (industry-standard Autodesk exchange formats), .skd (older AutoSketch drawing format), .wmf (Windows Metafile, also supported by AutoSketch) |
| Released | AutoSketch - Autodesk's entry-level 2D CAD/drawing program (1980s onward) |
| Latest version | AutoSketch 10 (last release; product line now discontinued by Autodesk) |
SKF conversions
Community Q&A
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