Tiny Online Tools
What this tool answers
Slicers are forgiving right up until they are not. A model with a hole in it will slice into something hollow and wrong; a wall thinner than your nozzle will simply vanish; a part 2 mm too tall will be silently clipped or refused at the printer. This checker asks all of those questions in one pass, before you waste a nine-hour print finding out.
Mesh health
Holes and non-manifold edges are the two hard failures. A printable model has to describe a closed solid: every edge shared by exactly two faces, no boundary edges anywhere. If either check fails, the slicer has no reliable way to decide what is inside the part and what is outside. Degenerate triangles, duplicate faces and inconsistent winding are softer problems — most slicers survive them, but they distort volume estimates and can produce stray extrusions.
Because an STL is unindexed triangle soup, the mesh is welded by spatial hash before any of this is measured. Skip that step and every edge in the file looks like a hole.
Print geometry
Build volume — your model's footprint and height against the bed. If it only fits after a 90° rotation, you are told that rather than just failing.
Wall thickness — estimated from the volume-to-area ratio, which is the honest way to catch hollowed or shelled parts. A wall thinner than one nozzle diameter cannot be extruded at all; under two, it prints as a single fragile bead.
Overhangs — every triangle's angle from vertical is measured against your support threshold, weighted by surface area rather than face count, and broken down into bands so you can see whether the geometry sits just past 45° or hangs fully horizontal.
Bed contact — the area of downward-facing surface inside the first layer. A tiny footprint on a tall model is the classic recipe for a part that snaps off mid-print and needs a brim or raft.
Minimum feature size — the thinnest dimension of the model compared with your nozzle. Embossed text, pins and thin fins below that size will not survive.
Units and orientation
STL and OBJ carry no unit information, so tell the tool whether the file is in millimetres, centimetres or inches. CAD exports are often authored Z-up; switch the build direction to match and the overhang analysis follows.
Privacy
Everything is computed in your browser. Your model never leaves the machine.