Many students in Germany have jobs in their spare time. Some may work as research assistants in universities, research institutes or libraries, while others may work as waiters or babysitters. International students also have the opportunity to work in addition to studying.
Students from third countries are permitted to work up to 140 full days or 280 half-days per year without requiring the approval of the Federal Employment Agency (BA). A working day of up to four hours counts as half a working day. Alternatively, both third-country students and students from EU/EEA countries and Switzerland may work up to 20 hours per week during the lecture period, just like German students. During the semester break, they can work without any restrictions.
These restrictions do not apply to student auxiliary tasks (e.g. academic work at higher education institutions).
International students may also complete internships or engage in self-employed activities while at university. However, any self-employed activity requires the approval of the competent foreigners authority. The authority will consider, among other things, whether the work is likely to hinder or delay the student in the pursuit of their academic goals.
You will find more information on the Deutsches Studentenwerk (German National Association for Student Affairs) website and at Study in Germany.