ChemBuddy
   Calculators for pH, solution preparation and concentration conversion, acid-base equilibrium, buffer, hydrolysis, and dilution calculations.
   http://www.chembuddy.com/

Chemical Calculator
   Free Windows program for calculateing conversion factors between compounds, concentration, and amount of substance in solution.
   http://freenet-homepage.de/buick/

Chemistry Functions
   Molar conversions and an interactive periodic table directly on the webpage. Requires JavaScript.
   http://www.umass.edu/ednet/chemistry.html

Elem
   Free program for the interpretation of elemental analysis results. For Windows and Unix; source code available.
   http://zarbi.chem.yale.edu/~ivan/elem/

JFormula
   Information System intended to support multi-stepped technological processes that can be defined on a table of mixes and ingredients and do not involve chemical reactions. The system includes an algorithm to calculate material requirements.
   http://www.jformula.com/BOMHome.html

Laborant Chemstation
   English version of German freeware data analysis program, for various calculations including stoichiometry, pH, thermochemistry, and kinetics.
   http://www.lcs-chemie.de/english.htm

MS Tools
   Online exact mass calculator, mass spectrum generator, and isotope distribution calculator.
   http://www.sisweb.com/mstools.htm

Norgwyn Montgomery Software
   NGMSI sells software for 3-D molecular modeling, chemical database creation and manipulation, 2-D publication quality drawing, calculation of over 100 physical properties from structure, automatic chemical internet database generation, and QSAR and QSPR a
   http://www.norgwyn.com

Physicochemical Calculators
   Simple online and offline calculators for boiling point at reduced pressure, unit conversion, and molecular mass.
   http://www.trimen.pl/witek/calculators/calculators.html

Reagent Calculator
   Windows software for the calculation of molecular weight, molecular formulas, mass percentages, mass spectroscopy fragments and adducts, and elemental analysis component; also includes a reagent library.
   http://members.empowering.com/gwfran/rgntcalc/

Visual MINTEQ
   A free equilibrium speciation model, which calculates chemical equilibria in aqueous systems at low ionic strength.
   http://www.lwr.kth.se/English/OurSoftware/vminteq/index.htm