I'm looking for free software for EEG data processing. What free or opensource software packages are available for analyzing raw EEG data?
The eegkit package for R is a good and open source toolkit for data analysis. It is easy to use and you can get really cool plots.
The main programs in the field are: Fieldtrip and EEGLAB. These are MATLAB-based but can be run on Octave (opensource implementation of basic MATLAB) which would be a good suggestion if you ever have any intent on working with other people looking at EEG data in research institutions etc.
The only other real alternative is MNE (Python-based), as suggested above. I use both EEGLAB and MNE for different things and I think having the ability to use both is definitely beneficial. If you are more used to the Python way of doing things then this might be your best option, although it's not as beginner-friendly as something like EEGLAB (but might be more intuitive if you've never used MATLAB-style coding before).