ChemCalc - Online calculator for molecular formula, molecular weight, elemental composition, and isotopic distribution. Java recommended.

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.

Mole Calc - Free software for Windows for the calculation of molecular weights. Also available in French.

Chemistry Functions - Molar conversions, balancing of equations, and an interactive periodic table directly on the webpage. Requires JavaScript.

McDalton - Free formula mass calculator for Windows, uses the latest values of atomic weights as recommended by IUPAC. For educational purposes, shows calculations as well as the uncertainty of the result.

ChemBalance - A windows program for balancing chemical equations.

Elem - Free program for the interpretation of elemental analysis results. For Windows and Unix; source code available.

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.

Physicochemical Calculators - Simple online and offline calculators for boiling point at reduced pressure, unit conversion, and molecular mass.