Grassroots DiCoM (GDCM) is a C++ library for DICOM medical files. It supports ACR-NEMA version 1 and 2 (huffman compression is not supported), RAW, JPEG, JPEG 2000, JPEG-LS, RLE and deflated transfer syntax. It comes with a super fast scanner implementation to quickly scan hundreds of DICOM files. It supports SCU network operations (C-ECHO, C-FIND, C-STORE, C-MOVE). PS 3.3 & 3.6 are distributed as XML files. It also provides PS 3.15 certificates and password based mechanism to anonymize and de-identify DICOM datasets.