Open STL Files Online
STL describes a 3D surface as a list of triangles, without colors or units. It is the standard format for 3D printing and comes in a binary and a text (ASCII) variant.
Stereolithography mesh · .stl
What you see in the STL viewer
- Exact dimensions, volume and surface area in mm or inches
- A watertight check that marks open edges in red
- Filament weight and cost estimate
- A bed-size check for common printers
Other ways to open STL files
Windows
Windows includes 3D Viewer on many versions; slicers like Cura and PrusaSlicer open STL too.
macOS
Quick Look and Preview show STL files.
Phone & tablet
Few phones open STL natively; this viewer works in the mobile browser.
Frequently asked questions
Is my STL file uploaded?
No. The file is read by your browser and shown on your own device. Nothing is sent to a server, and it is gone when you close the tab.
How do I open an STL file without installing software?
Drop the .stl file on this page. It opens straight away in the STL Viewer & 3D Print Check, on Windows, macOS, Linux, Android and iPhone alike.
What if my STL file doesn't open?
The viewer checks the file's content, not just its name. If it is damaged or not really an STL file, you'll see an error or can switch to the hex view to look at the raw bytes.