Download

CoolProp x64 is an open-source, free property database that includes pure fluids, pseudo-pure fluids, and humid air properties. It is designed to be trivially simple to use from the Python programming language, and possible to use from other languages as well.

CoolProp is a C++ library that implements:

Pure and pseudo-pure fluid equations of state and transport properties for 122 components
Mixture properties using high-accuracy Helmholtz energy formulations
Correlations of properties of incompressible fluids and brines
Computationally efficient tabular interpolation
Highest accuracy psychrometric routines
User-friendly interface around the full capabilities of NIST REFPROP
Fast IAPWS-IF97 (Industrial Formulation) for Water/Steam
Cubic equations of state (SRK, PR)

Programming Languages:

Fully-featured wrappers: Python (2.x, 3.x) ,`C++ (as static library) `, C++ as shared library , Modelica, Octave, C#, VB.net, MathCAD, Java, Android, MATLAB
High-level interface only: Labview, EES, Microsoft Excel, LibreOffice, Javascript, PHP, FORTRAN, Maple, Mathematica, Scilab, Delphi & Lazarus, Julia
Architectures:

32-bit/64-bit
Windows, Linux, OSX, Raspberry PI, VxWorks Compact Rio, etc. (if you can compile C++ on it, CoolProp will run)