Using characters in your engine

No Blender round trip is needed: the exports load directly.

Engine Use Notes
Unity FBX Imports natively; the Mixamo bone names map to the Humanoid rig. Tick Loop Time on looping clips. GLB in Unity needs the glTFast package. For lip-sync, see Faces (uLipSync, Meta's lip-sync plugin).
Unreal 5 FBX The skeleton has no separate root bone above Hips (like Mixamo), so Unreal's root-motion setup may need one added. Blend shapes import as morph targets.
Godot 4 GLB Loads the rigged, animated GLB directly. Tick Mark looping clips in their names in the Export panel: clips are then named Walk-loop and so on, which Godot imports as looping automatically. Rhubarb Lip Sync works for dialogue.
Web (three.js, Babylon.js, PlayCanvas) GLB Loads directly. npm run test:gltf proves this for three.js: it exports through the real pipeline, loads the file with the stock GLTFLoader + AnimationMixer in headless Chrome, and checks every bone of every clip against the generator. Results for all four rig variants: within 0.04°, with exact root positions, and the skinned mesh deforms.
Blender GLB or FBX Both import with the rig, animations and shape keys. scripts/blender_*.py show scripted imports.

Every engine:

Notes for other engines and tools are welcome; see CONTRIBUTING.md.