The homalg project is a multi-author multi-package open source software project for constructive homological algebra.
Mainly written in GAP4 it allows the use of external programs and other computer algebra systems (CASs) for specific time critical tasks.
Although the central part of the source code is the formalization of abstract notions like Abelian categories, our focus lies on concrete applications ranging from linear control theory to commutative algebra and algebraic geometry.
A big part of the project is already distributed with GAP. The yet undeposited packages and the tested development versions of all packages can be downloaded from the project GitHub homepage.
The core part of the project is the homalg package. It provides an abstract structure and algorithms for abelian categories.