Active Geochemistry Software Inc.
Groundwater chemistry and water geochemistry software for aqueous geochemical data analysis. Product overview, pricing, and on-line ordering. A downloadable demo version is available.

PHREEQC
US Geological Survey computer program for low-temperature aqueous geochemistry calculations such as speciation, batch-reaction, and one-dimensional transport. Downloadable software, complete on-line user's guide, FAQ, and installation information. Versions available for Windows, Mac, Linux, Sun, and generic UNIX.