An AI-generated GLB
Our own Stable Fast 3D output. The mesh is closed, but it is 94 cm tall, a size the generator picked for itself. Scale it before printing.
Free online GLB viewer
Inspect GLB and glTF files directly in your browser. The same viewer also opens OBJ, STL and PLY files.
Drag and drop a 3D file here, or
Supported formats: GLB, glTF, OBJ, STL, PLY.
Mesh check
Checked in your browser. Nothing is uploaded.
Files are processed entirely in your browser and never leave your device. For textured models use .glb, which packs geometry and textures into a single file.
Try it on a real file
An STL with a hole and loose bits
A sphere with part of its surface missing and two stray triangles. The check flags the hole, the open edges and the extra shells before a slicer does.
A clean, printable part
A closed robot model in one piece. This is what a file ready for the slicer looks like: closed, one shell, and the only amber lines are the unit and the texture coordinates, which an STL never carries.
What the mesh check tells you
Holes
Edges that belong to only one triangle mark a gap in the surface. A slicer cannot tell inside from outside until it is closed.
Non-manifold edges
An edge shared by three or more faces has no clear inside. Repair tools refuse these or guess, so it is worth knowing before you start.
Separate shells
Pieces that touch nothing else. Sometimes they are real parts, often they are debris, and either way they get printed.
Size and units
GLB is in metres; STL and OBJ state no unit and slicers read millimetres. The size line shows what your slicer will see.
Questions
Is my file uploaded anywhere?
No. The model is opened and checked by code running in this page, on your device. Nothing is sent to a server, and the page keeps working if you go offline after it has loaded.
Why does my STL show thousands of vertices before welding?
STL stores each triangle with its own copy of every corner, so a corner shared by six triangles is written six times. The check merges matching corners before it looks for holes, which is why a closed STL is reported as closed.
My model looks fine. Why does the check say it is not watertight?
Gaps can be smaller than a pixel on screen. The check counts edges that belong to only one triangle; even one makes the surface open. The hole count tells you how many separate gaps those edges form.
Which files can it open?
GLB, glTF with its data embedded, OBJ, STL and PLY. An OBJ opens without its MTL and textures, and a glTF that points to separate files needs those files, which a single upload cannot provide.