A model is not a character
until it moves.

It gives a 3D model a skeleton, and then lets you animate it. You do not need a model to start: open a blank canvas and describe the one you want, or give it a photo, and it is generated onto the stage — that spends credits — or start from the plain humanoid body Skeleton builds for you in the browser. A model you have generated here, or a .glb off your disk, works too. From there you fit a humanoid rig to the mesh, refine the joints by hand, let it paint the skin weights, then keyframe as many named clips as you need on a timeline — walk, idle, attack — and export the lot as one rigged, animated file. It is the step between having a model and having a character.

No — and you do not have to have one. Open a blank canvas and describe the model you want, or give it a photo, and one is generated onto the stage for you, which spends credits. Or Skeleton can build a plain humanoid starter body for you in the browser, with nothing sent anywhere. Otherwise it opens a model straight from your own library of generated models, or takes a model file off your disk and reads it in the browser — there is no upload step for a model file, so a .glb you open from your own machine never leaves it. The skeleton fit, the skinning, the timeline and the export all run client-side as well. Two optional actions do not. Making a model sends your words to a 3D generator, or uploads the photos you chose for it and sends those — never a model file off your disk. And the AI auto-rig sends a model already stored in your library to a rigging service, which is the whole reason it is a separate, clearly-marked, paid action — it is never offered for a file you opened off your own disk, because that mesh only exists in your browser.

A glTF binary — a .glb — with the skeleton, the skin weights and every clip inside it, plus optional PNG sprite sheets. Not FBX, and we would rather say so on this page than in a tooltip after you have done the work: there is no browser-side FBX writer that can carry skinning or animation at all, so an FBX button here would have to quietly hand you something else. Unity, Unreal, Godot and Blender all import glTF directly.

Yes, as a Generic rig. This is a limit of the format rather than of the export: glTF has no way to carry a Humanoid Avatar, so Unity cannot build one from it and your clips play through the legacy Animation component instead of Mecanim. Everything else comes across — the skeleton, the weights and every clip. The Unity preset says this on screen as well, because it is the sort of thing that should not be a surprise.

Both are straightforward. The Unreal preset writes the file the only way a glTF may be written — Y-up and in metres — and leaves the Z-up, centimetre conversion to Unreal, whose importer does it unconditionally because the file is not permitted to have done it already. What the preset adds is the part an importer cannot work out for itself: the UE5 mannequin bone names, and a root bone at the origin so root motion has something to attach to. The Godot preset keeps metres and Y-up, turns the character to face −Z the way Godot itself does, and uses the Unity HumanBodyBones names — the same list Godot 4 calls SkeletonProfileHumanoid, which is what its importer maps against. Picking a preset changes the export and the viewport gizmo together, so what you are looking at is what you will get.

For 2D. You can render any clip out as a sprite sheet — an orthographic turntable of 1, 4, 8 or 16 directions, at a side-scroller, isometric, true-isometric, action-RPG or top-down camera angle — with one bounding box across every frame so the character does not change size when it turns, and the pivot taken from the projected hip bone rather than the transparent edges, which is what stops the feet bobbing between animations. The zip carries the sidecars too: an Aseprite-style frame JSON, Unity sprite pivots, a Godot SpriteFrames resource, optional GameMaker strips and a manifest describing every file in it. It is the only route into an engine with no 3D skeletal import at all.

Humanoids, standing in a T-pose or an A-pose, facing roughly forward. That is what the humanoid skeleton is shaped for, and the pre-flight check tells you what it found — the pose, the scale in metres, the forward axis and how confident it is about the symmetry plane — before you commit to anything, with one action to normalise the axis, the scale and the origin if they are off. Non-humanoid meshes are not what this profile is for. A prop — a door, a coin, a crate — can still be animated as one piece in Object mode, with no skeleton at all.

Yes, with three clearly-marked exceptions. Fitting the skeleton, painting the weights, the whole timeline, the glTF export and the sprite renderer are free and always will be, because there is nothing to charge for: they run in your browser, no model runs and no server does the work. The first is the optional AI auto-rig, a single button inside the editor that hands your model to a rigging service and gets a finished, skinned skeleton back — that one is a real bill and it spends credits. You never have to press it; the manual route does the same job for nothing. The second is the motion library, a shelf of ready-made animations — walk, run, jump, pick up, attack — that you drop onto your rig as clips: five of them are free to everyone and the rest come with any subscription. You can watch every animation in it move before you decide, and you can always key your own by hand for nothing. The third is generating a model — describing it, or starting from photos, in the Create step — which sends your description or photos to a 3D generator and puts the result on the stage, a way to start with nothing of your own. That spends credits too, and the model it makes is saved to your models. The starter body is not one of the three: Skeleton builds it in your browser rather than asking a generator for it.

Yes. The editor lays itself out for the screen it is on. On a phone the stage sits at the top, the step you are on scrolls underneath it, and a bar along the bottom moves you between Create, Prepare, Rig, Animate and Export; on a tablet the panel sits beside the stage. Drag with one finger to orbit, pinch to zoom, and tap a joint — or press and hold on it — to select it. Detailed joint work and weight painting on a busy mesh are still easiest with a mouse and a bigger screen, and your project is saved, so you can start on a phone and finish on a computer. Any modern browser with WebGL runs it.