I got the chance to contribute a feature to an existing open source project as part of my uni studies during this semester. Ideally the project would be an end-user project, not a library, and not something that I'm already contributing to anyway.
Language-wise, C++, Rust or Haskell would be nice.
Do you know any projects that would fit?
My own idea are a bit too KDE-centric, but the point of this module is to contribute somewhere I'm not already part of.
Year after year, Hacktoberfest lists resources for beginners on how to find a good repository:
Some of the sites listed there allow filtering.
notmuch  is a mix of C (mostly) and C++ (lower level interface to Xapian). There is also python bindings and an emacs-lisp front end. It's very much not KDE 😉. I like to think we are welcoming to new contributors, although we do sometimes need a few rounds of code review (and e.g. adding tests and documentation) before new features are integrated.
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