STL Viewer Online — Free, Browser-Side, No Upload
STL → view
View and inspect STL files in your browser. Rotate, zoom, and pan 3D models. Supports files up to 200MB. Free, private, no upload required.
Best for
- Quickly checking whether an STL file opens before slicing or printing
- Inspecting model orientation, proportions, and obvious mesh problems
- Viewing customer or downloaded STL files without installing desktop software
- Reviewing private models locally without server upload
Before you start
- Use the viewer for visual inspection; it does not replace slicer printability checks
- Treat displayed dimensions as raw coordinates because STL does not define units
- Expect gray geometry only because STL has no material or texture data
- Close other heavy browser tabs before opening very large STL files
Known Limitations
- STL files have no unit metadata — displayed size reflects raw coordinate values
- No materials or textures — STL is geometry only
- Files over 200MB may trigger an in-browser memory warning; performance depends on device
Helpful guides
Frequently Asked Questions
What is the maximum file size I can view?
There is no hard limit, but very large files may slow down or stall depending on your device memory and browser. If you hit a slowdown, try a smaller file or close other tabs.
Does the viewer show textures and colors?
No. STL stores geometry only — it has no color, material, or texture data. The viewer renders the mesh with a default gray shading. If you need color, use a format like GLB or OBJ with MTL.
Does my STL file get uploaded to a server?
No. The file is loaded and rendered entirely inside your browser using Three.js. Your file never leaves your device.
The dimensions shown do not match what I designed. Why?
STL has no unit metadata — the viewer displays raw coordinate values. If your model was designed in millimeters and the values appear large, the coordinates are still correct; the viewer just has no way to label them as mm or inches.
Can I measure distances or check wall thickness in the viewer?
The current viewer supports rotate, zoom, and pan only. Measurement and wall-thickness analysis are not available. For those checks, Meshmixer or PrusaSlicer are good free options.
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.