The development of multicore architectures supporting parallel data processing has led to a paradigm shift, which affects communication systems significantly. This article provides a scalable parallel approach of an iterative LDPC decoder, presented in a tutorial-based style. It is suitable for decoding any irregular LDPC code without the limitation of the maximum node degree, and it includes a parallel calculation of the syndrome. This is the main difference from algorithms presented so far. The proposed approach can be implemented in applications supporting massive parallel computing, such as GPU or FPGA devices. The implementation of the LDPC decoder with the use the OpenCL and CUDA frameworks is discussed and the performance evaluation is given at the end of this contribution.