STL to OBJ Converter — Free, Browser-Side, No Upload
STL → OBJ
Convert STL files to OBJ format instantly in your browser. No upload, no account. Supports binary and ASCII STL. Free and private.
Use this when
- Audience
- Makers and modelers searching for STL to OBJ conversion when they need editable or shareable mesh geometry.
- Task
- Turn a 3D printing STL into a geometry-only OBJ without sending the model to a cloud converter.
- Successful outcome
- Download the OBJ, open it in the target modeling tool, and verify scale because STL has no units.
- Boundary
- This does not create materials, textures, object hierarchy, or a CAD solid from the STL.
Best for
- Opening an STL mesh in OBJ-friendly modeling tools
- Sharing simple geometry with users who cannot import STL
- Inspecting or editing triangle mesh geometry without uploading the file
- Creating a geometry-only OBJ from a 3D printing STL
Before you start
- Check the model scale after conversion because STL has no unit metadata
- Expect geometry only; STL cannot provide materials, colors, or textures
- Use a mesh repair tool first if your STL fails to open in slicers or viewers
- Large triangle-heavy models may take longer on low-memory devices
Next steps
Known Limitations
- No units — STL stores raw coordinates with no unit metadata; confirm scale after conversion
- No materials — STL has no material or texture support
- No textures — texture data is not present in STL
- No hierarchy — STL has no scene graph or object grouping
- Triangles only — STL stores triangle meshes; curved surfaces are approximated
- OBJExporter does not export MTL material files; geometry only, materials/textures are lost
Helpful guides
Frequently Asked Questions
Does this converter support both binary and ASCII STL files?
Yes. Three.js STLLoader detects the format automatically — both binary and ASCII STL files are parsed without any extra steps on your part.
How do I convert an STL file to OBJ?
Choose your STL file, let the browser parse the mesh locally, then download the generated OBJ file. The result is geometry-only because STL does not contain materials, colors, textures, units, or object hierarchy.
Will my materials or textures carry over to the OBJ file?
No. STL stores geometry only — it has no material, color, or texture data. The OBJ output will be geometry-only. If you need materials in OBJ, start from a format that includes them, such as GLB.
What is the file size limit?
There is no hard server-side limit because conversion runs entirely in your browser. Very large files (100 MB+) may be slow or cause a memory warning depending on your device.
Does my file get uploaded to a server?
No. The entire conversion runs inside your browser using Three.js. Your file never leaves your device — there is no server upload, no cloud storage, and no third-party processing.
Why does the OBJ output have no .mtl file?
The Three.js OBJExporter doesn't generate MTL files, and STL input has no material data to export anyway. The OBJ file contains geometry only.
Related tools
How it works
Your files are processed entirely inside your browser using Three.js. Your files never leave your browser — there is no server upload, no cloud storage, and no third-party processing. The converted file is generated as a local Blob and downloaded directly to your device. Once the conversion is complete, all data is released from memory.