RAVE
Reproducible Analysis and Visualization of intracranial EEG (RAVE) is free and open-source software for the analysis of intracranial electroencephalogram (iEEG) data, including data collected using strips and grids (electrocorticography, ECoG) and depth electrodes (stereotactic EEG).
YAEL
Your Advanced Electrode Localizer (YAEL) is free and open-source software for localizing and visualizing electrodes.