Yes, the Godot engine is open source. It's released under the MIT license, which means it's free to use for any purpose, including commercial projects.
Godot's source code can be accessed and modified by anyone who wishes to understand its underpinnings or contribute to its development. This openness encourages a collaborative community environment where developers can contribute bug fixes, enhancements, or new features.
The engine is primarily developed in C++, but it allows for the use of GDScript, Visual Scripting, C#, and C++ for creating gameplay and logic. Here's a very basic example of how a script might look in Godot, using GDScript:
You can access the Godot source code from the GitHub repository at
https://github.com/godotengine/godot. Before contributing to the project, it would be advisable to read Godot's contribution guidelines, found in the same repository.