The UNILIB library has initially been developed by the Royal Belgian Institute for Space Aeronomy (BIRA-IASB) in the framework of the ESA's Trapped Radiation ENvironment Development (TREND) projects and was later on integrated in ESA's SPace ENvironment Information System (SPENVIS). It implements a series of tools for coordinate transformations, magnetic field computation, magnetic coordinate evaluation, magnetic field line and drift shell tracing, etc.

The UNILIB libray was build in the late 90s in an effort to improve the radiation environment models and the software used to predict the radiation environment experienced by satellites in orbit around the Earth. The software library therefore implements tools to compute the geomagnetic field, to trace magnetic field lines and drift shells, and to evaluate averaged quantities along a drift trajectory. It allows to compute specific coordinates for the geomagnetically trapped particles such as the magnetic field intensity at the mirror points Bm, the McIlwain parameter LM, the third adiabatic invariant, the Roederer parameter L*, the altitude of the lowest mirror point hmin, etc. The software library is developed in FORTRAN.

Access to the UNILIB software should be requested to the European Space Software Repository at https://essr.esa.int/.