.stl File Extension
.stl file contains, which applications open it, and how Poly supports this 3D format. File extension details for .stl
Full Support| File type | STL stereolithography model |
|---|---|
| MIME type | |
| Encoding | ASCII text or binary |
| Operating systems | Windows, macOS, Linux |
| Opens with | Cura, PrusaSlicer |
| Poly support | Yes. Poly recognizes valid STL stereolithography model files and makes supported geometry available in the file experience. |
| Indexed by Poly | Yes. Poly indexes the filename and creates visual similarity information for supported 3D content; available metadata is shown in details. |
| Preview in Poly | Yes. Poly previews supported STL stereolithography model geometry. |
| Poly agent | Yes. An optimized rendition of the 3D object or scene is provided to the agent, allowing compact yet information-rich multimodal interaction with 3D files. |
What kind of file is a .stl?
STL represents a surface as a collection of triangular facets. ASCII STL uses solid, facet, and vertex records; binary STL stores an 80-byte header, a triangle count, and fixed-size triangle records. STL describes shape for fabrication, not a complete scene. The suffix normally uses the model/stl MIME type.1
How do I open a .stl?
Cura and PrusaSlicer can import STL stereolithography model files on desktop systems; Blender is another practical choice for conversion when its importer supports the asset. Keep any companion resources with the model, and validate scale, winding order, and whether the surface is closed before sending it to a print or CAD workflow.
Export to GLB for a scene package with richer materials and animation, or to 3MF for additive manufacturing when package metadata matters. Renaming a suffix does not convert a file.
Poly support for .stl
Poly previews supported geometry, makes the filename searchable, and provides visual similarity for supported 3D content. Available geometry metadata appears in the details panel. An optimized rendition of the 3D object or scene is provided to the agent, allowing compact yet information-rich multimodal interaction with 3D files.
| Construct | Poly handling |
|---|---|
| Geometry | Triangular surface facets |
| Appearance | No standard textures, materials, scene hierarchy, or animation |
| Manufacturing | Useful for slicers after mesh repair and validation |
Keep the original source when exact topology, custom attributes, or companion-file relationships matter.
History and alternatives
3D Systems developed STL for stereolithography in the 1980s. Its broad printer and slicer support made it a durable exchange format, even though it carries little appearance or project information. 1
Use glTF or GLB for interactive scenes, 3MF for manufacturing packages, and STL when a simple triangular surface is enough. Convert in a 3D application and verify the exported model rather than relying on a filename change.
Footnotes
- Library of Congress. STL file format. ↩ ↩2