Tiny Online Tools
What breaks in a rig, and where
A rigged model that looks fine in one viewer and explodes in another is almost never a mesh problem. It is a skinning problem, and skinning problems live in three places: the bone hierarchy, the skin weights, and the inverse bind matrices. This tool reads all three straight out of the file.
Influence counts
Every vertex is bound to some number of bones. Real-time pipelines cap that number — four is the near-universal limit, and several mobile and WebGL paths prefer two. The Influences tab gives you a histogram: how many vertices use one bone, two, three, four, and how many carry no weights at all.
That last bucket matters most. A vertex with all-zero weights collapses to the bind position the moment skinning is applied, which shows up as a torn face or a spike shooting off into the distance. It is invisible in the bind pose and obvious on the first animated frame.
glTF can declare more than four influences per vertex with additional JOINTS sets. Almost nothing loads them. When the file does that, the tool says so, because it means the deformation you approved in the authoring package is not the deformation anyone else will see.
Bones that do nothing
A bone that influences zero vertices still occupies a slot in the skinning uniform buffer and still gets updated every frame. Whole finger chains routinely survive an export while every vertex in the hand is bound to the wrist. The Bones tab shows the influenced vertex count and total weight per bone, so dead bones sort straight to the bottom.
Inverse bind matrices
Each joint stores a matrix that undoes its bind transform. The checks here are concrete: is there one matrix per bone, is any of them non-invertible or full of NaN, and — the useful one — does the bone's world matrix multiplied by its inverse bind matrix come out as the identity? It should, when the file is stored in its bind pose. A large deviation is legal but it is the first thing to look at when a character deforms as though it were folded in half.
Names and roots
Duplicate bone names are legal in glTF and fatal for retargeting, since every retargeting system addresses bones by string. More than one root bone in a single skeleton usually means an export accident. Both are flagged.
Private by design
Parsing runs entirely in your browser. Nothing is uploaded, so unreleased characters and NDA'd client rigs stay on your machine.