GDExtension is a Godot-specific technology that lets the engine interact with native shared libraries at run-time. You can use it to run native code without compiling it with the engine.
GDExtension is not a scripting language and has no relation to GDScript.
Docs
Limitations
- Not compatible with pre-Godot 4
- GDExtension add-ons compiled for a given Godot version are only guaranteed to work with the same minor release series. For example, a GDExtension add-on compiled for Godot 4.0 will only work with Godot 4.0, 4.0.1, 4.0.2.
- GDExtension add-ons are also only compatible with engine builds that use the level of floating-point precision the extension was compiled for. This means that if you use an engine build with double-precision floats, the extension must also be compiled for double-precision floats. See Large world coordinates for details.
GDExtensions are experimental
Our long-term goal is that GDExtensions targeting an earlier version of Godot will work in later minor versions, but not vice-versa. For example, a GDExtension targeting Godot 4.2 should work just fine in Godot 4.3, but one targeting Godot 4.3 won’t work in Godot 4.2.
However, GDExtension is currently experimental, which means that we may break compatibility in order to fix major bugs or include critical features. For example, GDExtensions created for Godot 4.0 aren’t compatible with Godot 4.1 (see Updating your GDExtension for 4.1).