OPAL (Object Oriented Parallel Accelerator Library) is an open source C++ framework for general particle accelerator simulations including 3D space charge, short range wake fields and particle matter interaction. OPAL is based on IPPL (Independent Parallel Particle Layer) which adds parallel capabilities. Main functions inherited from IPPL are: structured rectangular grids, fields, parallel FFT and particles with the respective interpolation operators. Other features are, expression templates and massive parallelism (up to 65000 processors) which makes it possible to tackle the largest problems in the field. A new Trilinos based iterative solver - currently in the commissioning phase - handles arbitrary complex boundary conditions and benefiting from the new geometry class.