Free online STL viewer
Drop an .stl, text or binary, and turn it around. The page counts the triangles and reads the size out of the numbers in the file; your browser draws it and nothing is sent anywhere.
How to look at an STL
- Drop the .stl on the page or pick it with the button. Text and binary files are told apart by their contents.
- Orbit with the mouse and zoom with the wheel. A part lying on its back was written Y-up by a game tool: the Z-up / Y-up button stands it up.
- Read the panel: triangles, the box the part fits in along X, Y and Z, and the size of one grid square for scale.
What an STL is
An STL is triangles and nothing else: three corners and a normal per face, no shared vertices, no names, no materials, no colour, no unit. The binary form spends 50 bytes per triangle, the text form four or five times that for the same picture. Whether a 25.4 means millimetres or inches was decided by whoever exported it; slicers assume millimetres.
What the page does not do
It shows the surface and does not judge it: no check for holes, flipped normals or non-manifold edges, no repair, no measuring between two points. A slicer does those on the same file.
Frequently asked questions
Can an STL become a VTuber avatar?
Not as it is. An avatar needs a skeleton, skin weights and a face that moves; an STL is a surface. A character sculpt saved as STL has to be retopologised, textured and rigged in Blender, then exported as FBX or GLB for the VRM converter.
What unit is my STL in?
The file does not say. The numbers are shown as they are and labelled units, not guessed. A part modelled in inches opens 25.4 times too small in a slicer that assumes millimetres.
Why is everything grey?
Because STL holds no colour, material or texture. For colour in printing use 3MF; for screens, GLB or OBJ with an .mtl.
Does binary or text matter?
Only for size and speed. Both hold the same triangles; the panel says which one you dropped.
How large a file opens?
Up to 300 MB, which for a binary STL is about six million triangles. A text STL of the same size holds far fewer and takes longer to parse.
Is the file uploaded?
No. It is read from your disk and drawn with WebGL. After the page has loaded you can go offline.
The same mesh in another format
The STL to GLB converter writes the triangles into a .glb for engines and web viewers. It adds nothing the STL never had: the result is one untextured mesh.