surfit is a computer program which enables to calculate regular grid from various data (scattered points, curves, surfaces, etc), conditions and inequalities by setting called gridding rules. surfit implements the original gridding method. surfit is an Open Source and Free Software, the source code is available free of charge under the Free Software GPL license. The code is written in C++ with STL usage. Careful attention is paid to performance related issues. The initial goal of surfit is to provide an efficient tool to scientists dealing with gridding computational tasks.