What is an MJCF file?

MJCF is the XML model format used by MuJoCo, the physics engine widely used in robotics and reinforcement-learning research. It describes a tree of bodies with joints and primitive collision/visual geoms.

My MuJoCo model is a .xml file — will it open?

This viewer is registered for the .mjcf extension. Rename a MuJoCo .xml to .mjcf, or open this page and drop it directly. MJCF models that use inline geoms (most do) render fully.

No. The model is parsed and rendered entirely in your browser. Nothing is sent to a server.

Does it work on mobile?

Yes. The viewer is mobile-first and works on phones, tablets, and desktops.

3D & Geometry.mjcf

MJCF viewer

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MJCF · .mjcf

Open MJCF files

MuJoCo XML — physics & robot models.

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About MJCF

MuJoCo XML — physics & robot models.

MJCF is MuJoCo's XML model format — a worldbody of nested rigid bodies, each carrying joints and inline geoms (box, capsule, cylinder, sphere, ellipsoid). Because MuJoCo models lean on inline primitives rather than external meshes, MJCF renders especially well single-file: we rebuild the body tree in three.js with the correct half-extent geom sizing, all locally in your browser.

FAQ

What is an MJCF file?: MJCF is the XML model format used by MuJoCo, the physics engine widely used in robotics and reinforcement-learning research. It describes a tree of bodies with joints and primitive collision/visual geoms.
My MuJoCo model is a .xml file — will it open?: This viewer is registered for the .mjcf extension. Rename a MuJoCo .xml to .mjcf, or open this page and drop it directly. MJCF models that use inline geoms (most do) render fully.
Is my file uploaded?: No. The model is parsed and rendered entirely in your browser. Nothing is sent to a server.
Does it work on mobile?: Yes. The viewer is mobile-first and works on phones, tablets, and desktops.

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