As a French student in highschool, how can I enter a good university in the UK or US?

Your best bet is to contact the schools directly and ask if they can put you in touch with current students that went to high school in France.  They will have the best idea of the attributes of students that did or did not get in.  Most Americans, including myself, have only the vaguest idea of the content of European education systems at any level.  I have been told, anecdotally, that it is less difficult to be accepted by at least one top-10 engineering school than be accepted to the grandes écoles of France, but I have no evidence to back that claim. I'm assuming you'd be interested in a computer science or engineering program, based on your mention of MIT and your personal projects.  I went to the University of Illinois at Urbana-Champaign, which generally has a US rank among the top 5 for bachelor's in electrical/computer engineering and top 10 for computer science bachelor's degrees.  My personal opinion, based on my experiences with admissions officers of my university and department: Highly reputable US universities (top-5) will look at your performance during all years of high school, with a slight emphasis on the later years. They will put more emphasis on high school performance than standardized test scores, since it is generally a better indicator of academic success.  Because admissions are competitive, however, nearly all accepted students will have very high standardized test scores. They will want you to be prepared in your coursework, which means all mathematics up to calculus for engineering, and the basic sciences, and they will look at your scores if available. Given the lack of extracurriculars, personal projects will tip the odds in your favor, especially if you are applying to a computer science/engineering program. The section may not matter much: US education leans heavily towards liberal arts compared to other countries.  Engineering and computer science students will start with the first, second, or third semesters of calculus, and introductory calculus-based physics, depending on the school. Other than that, there is probably quite a bit of flexibility and you will be interesting to the admissions officers, especially at the non-Ivy League schools, because you increase the diversity of the student body (compared to the masses of US-born students).  A close friend who has done admissions at Harvard has told me of rejected students that were academically perfect but did not seem like people who could bring unique contributions to the school. Community or smaller state colleges can be a path into the top schools, especially if your high school scores are not the best, or if you're trying to preserve your money.  I have several friends who have taken that path, although I'm only aware of transfers into the top state schools (U-C Berkeley, Illinois).  Employers generally care only about your last degree/school.  The reputation of the school opens many doors, as do the connections.  I have worked at both large companies and start-ups, and I'm always surprised at how much weight the name of the school carries.