Free · Private · Runs in your browser
Convert 3MF, STL and OBJ files for 3D printing, mesh editing and CAD exchange. Preview the model, pick the parts you need and download in seconds. Your files never leave your device.
Release to open the file
Tools
Every tool runs on the same in-browser engine, so they're fast, private and free. More converters are on the way.
Turn Bambu Studio, Orca and PrusaSlicer projects into STL files: one file, or one per object.
Work out filament, electricity, machine wear and labor per part, and what to charge for it.
Extrude logos, signs and Cricut designs into printable 3D models.
Turn PNG and JPG artwork into keychains, stamps and plaques.
Convert CAD files from Fusion, SolidWorks and Onshape to STL.
Close holes and fix broken meshes before you slice.
Formats
Drop any of these files into the converter. STL Kit reads it, shows you what's inside and writes the format you choose.
Projects from Bambu Studio, Orca Slicer, PrusaSlicer and Cura, including multi-part objects, plates, modifiers and filament colours. Written as clean, standard 3MF.
Binary and ASCII STL, including ASCII files with several solids. Written as compact binary or readable ASCII.
Wavefront OBJ meshes from Blender and other 3D apps, with one part per object or group. Set the units on import.
Format guide
Use 3MF when you need a slicer project with units, objects and production context. Use STL for a simple triangle mesh, or OBJ when your modeling workflow uses object and group structure. STL Kit lets you inspect the geometry before choosing an export format.
STL is a mesh format made of triangles. It describes the surface of a 3D object, but stores no units, colours, materials or printer settings. That simplicity makes STL widely supported by slicers and 3D software. When exporting a project to STL, the geometry remains while project-only information is left behind.
3MF means 3D Manufacturing Format. It is a ZIP-based package that can contain mesh geometry, units, object names, colours, materials and slicer data. Unlike STL, it can describe a complete project with several objects and plates. Keep a 3MF when that production context matters.
| Property | STL | 3MF |
|---|---|---|
| Geometry | Triangle mesh | Triangle mesh |
| Units and scale | Not stored | Stored |
| Colour and materials | Not stored | Can be stored |
| Objects and plates | Mesh only | Project structure |
| Slicer settings | Not stored | Can be stored |
| Best suited for | Mesh exchange | Slicer projects |
Working with a Bambu Studio, Orca or PrusaSlicer project? The dedicated converter covers multi-plate projects, modifiers and per-part export. Open the 3MF to STL converter.
Format references: 3MF Consortium specification · Library of Congress STL format description
How it works
Drag a 3MF, STL or OBJ file onto the converter, or click to choose one. The file opens in your browser and is never uploaded, so you can start without an account.
Orbit the 3D preview, check the size against your printer's bed, and review the mesh statistics. Untick any objects or helper volumes you do not need. The original file stays unchanged while you prepare the export.
Choose 3MF, OBJ, binary STL or ASCII STL as the output. Download one file, or separate objects or parts in a ZIP. Then open the result in your slicer, mesh editor or CAD tool and verify its scale and settings.
Why STL Kit
Not an upload form. STL Kit is a real mesh engine that runs on your own machine.
Files are read and written inside your browser tab. Nothing is uploaded, so confidential parts stay on your device.
Parsing runs in a background thread with native decompression, so million-triangle projects open in seconds without freezing the page.
Reads how Bambu Studio, Orca and PrusaSlicer store projects: part names, filament colours, plates and modifier volumes.
See the triangle count, volume, surface area and whether every part is watertight before you export.
Preview the model on the bed of popular Bambu Lab, Prusa, Creality, Elegoo and Anycubic printers.
No account, no watermark and no daily quota. Files up to 100 MB are supported; available device memory also matters.
FAQ
STL Kit converts between 3MF, STL and OBJ. You can preview the model in 3D, check its size and mesh, choose which objects to keep, and download one file or separate files for each object.
You can open 3MF, STL (binary and ASCII) and OBJ files, and save them as binary STL, ASCII STL, 3MF or OBJ. SVG, image, STEP and repair tools are coming next.
It's free, with no sign-up and no watermark. Files up to 100 MB are supported; the practical limit is your device's memory.
No. The conversion happens entirely in your browser, so your models never leave your computer. Once the page has loaded, it even works offline.
Drop the STL file into the converter. 3MF is already selected as the output for STL files, so click Download 3MF. If the STL wasn't made in millimetres, choose its unit under Model units first.
Binary is usually the best default. It holds the same triangles in a much smaller file and is widely supported by modern slicers and mesh tools. Choose ASCII STL when a specific workflow needs plain text.
STL and OBJ files don't store units, and slicers assume millimetres. If a model was made in inches, centimetres or metres, choose that unit under Model units before downloading, and STL Kit rescales it to millimetres.
A watertight mesh is a closed surface in which every edge joins exactly two triangles, with no holes. Slicers need closed shells to work out what is inside a part. STL Kit flags open edges so you know before you slice.