Tuition and/or registration fees will have to be paid, depending on the institution and on the situation of the student. A limited number of scholarships is available.
ETH Zürich: see the "Financial Aid office" website.
École polytechnique: As for the academic year 2017-2018, the fees amounted to 256€ per year, plus 217€ for (mandatory) social security (health care). A limited number of scholarships is available for students who plan to continue with a PhD in one of the labs hosted by École polytechnique; please visit the PhD program web page for more information.