PsiLAB has been developed for scientific research and data analysis. It is freely distributed in source code format under Gnu Public License, version 2. PsiLAB is written mainly in the functional language O'CaML developed at INRIA research laboratories. It's mainly made of three parts: 1) O'CaML itself, 2) libraries written in O'CaML, and 3) external libraries written in Fortran and C. PsiLAB uses the following external libraries, mainly written in Fortran: LAPACK - Linear algebra and linear least square problems, MINPACK - Non linear least square fits, PLPLOT - 2D and 3D plot library with several output drivers, FFTW - Fastest Fourier Transform in the West, AMOS - Special functions, SLATEC (partially implemented) - More special functions (Gamma  function,...), CamlImages (partially implemented) - Support for various image formats, and more.