HAP is a homological algebra library for use with the GAP computer algebra system, and is still under development. Its initial focus is on computations related to the cohomology of groups. Both finite and infinite groups are handled, with emphasis on integral coefficients.
Recent additions include some basic functions for handling simplicial and cubical complexes in the context of topological data analysis.
The current version 1.9 was released on 24 September 2009.
An overview of the library can be found here.