The talk at the FOSDEM conference in 2023 was given by Nicolas Vieille, a C++ developer at Kitware Europe. The talk focused on ParaView, an open-source application for scientific data analysis and visualization. ParaView can display and analyze scientific datasets in 3D, and also has features for data processing and realistic rendering. It is widely used in various domains such as fluid dynamics and medical applications. ParaView can be used through its graphical user interface or through Python scripting, and it is cross-platform, supporting Linux, Mac, and Windows. The talk also discussed the different modes of usage for ParaView, including running it on HPC infrastructure, where it supports a client-server architecture and parallel processing using MPI. In terms of performance, ParaView uses a thin layer for CPU parallelism, and optionally integrates with VTKM, a library for heterogeneous systems. The talk also highlighted the use of in-situ processing, where ParaView can directly analyze data from simulations without writing it to disk. This is done using ParaView's standalone API called Catalysts. The talk mentioned upcoming improvements, such as support for in-transit processing, better VTKM integration, and implicit arrays for memory optimization. The speaker also mentioned that ParaView has a web client called Trame and supports integration with Jupyter Notebooks. The talk concluded with a Q&A session where participants asked questions about using ParaView with GitHub Actions, setting up Catalysts in simulations, and the possibility of a web-based client for ParaView.