How the picks are chosen
A course must clear the eligibility rules first: the provider is an accredited university, an established platform or a company publishing its own training; the page is on the provider's official site; the course is free in full or free to audit in full, not a first-module preview or a trial; the page states the cost and the certificate terms; and the teaching stands on its own for someone studying alone, with complete lectures or readings and exercises or projects where the subject calls for them. Material must be current for its subject or a classic that still holds up.
Among eligible courses, the 30 picks are ordered by how far the course takes you, then how well the teaching works when watched alone, then whether the work is graded, with provider reputation breaking ties. Nobody can pay for placement, and affiliate or advertising status never affects whether a course appears or where. The full rules are in the editorial policy.
Which of the best free online courses come with a certificate
The certificate was not a criterion, which is why most picks have none. Harvard's CS50 courses are the exception: each makes you eligible for a free CS50 Certificate at a unique URL by scoring at least 70% on the graded work, and they hold the top of the list on teaching and depth rather than on the credential. Yale's The Science of Well-Being and Moral Foundations of Politics are free in full on Coursera with an optional paid certificate. Everything else, from MIT OpenCourseWare to Open Yale Courses, Stanford Engineering Everywhere, Oxford's open lectures and Princeton's Coursera courses, gives no certificate at any price.
Picks for programming and computer science
This is the largest group because it is where free university teaching is most complete: lectures, graded problem sets, exams and solutions.
Start here: CS50, MIT 6.0001 and Princeton's Java courses
CS50's Introduction to Computer Science is the first pick because it is a full university course with nothing paywalled: eleven weeks at 10 to 20 hours a week, from C through Python to SQL and web programming, ending in a project of your own. CS50's Introduction to Programming with Python is the pick for Python alone, ten weeks of graded problem sets with no software to install, and CS50's Introduction to Programming with Scratch is the gentlest entry in the family at nine weeks.
MIT's Introduction to Computer Science and Programming in Python is the OpenCourseWare alternative: lecture videos, slides, code and problem sets from a half-semester course for people with little or no prior experience. In Java, Stanford's CS106A publishes 28 lectures with assignments and exams, and Princeton's Computer Science: Programming with a Purpose is free in full on Coursera with assignments.
Go deeper: algorithms, systems and web programming
Princeton's Algorithms, Part I and Part II are the Sedgewick and Wayne courses, five weeks and six weeks of graded programming assignments in Java; Algorithms, Theory, and Machines is the second half of Princeton's introductory sequence. MIT's Introduction to Algorithms adds twenty-one recorded lectures with notes, problem sets and exams. Stanford's CS106B is a full data structures course in C++, and CS107 its systems and paradigms course, both with assignments and exams.
For building things, CS50's Web Programming with Python and JavaScript is nine weeks of Django and React projects ending in a deployable application, and CS50's Introduction to Databases with SQL takes SQLite to PostgreSQL and MySQL in seven weeks.
Picks for AI, data and mathematics
CS50's Introduction to Artificial Intelligence with Python is the project-based AI pick, covering search, optimisation, machine learning and language models in seven weeks at 10 to 30 hours a week. CS50's Introduction to Programming with R teaches R and the tidyverse with graded problem sets, and Stanford's CS223A Introduction to Robotics is a graduate foundations course with notes and problem sets whose only prerequisite is matrix algebra.
For the mathematics underneath, MIT's Linear Algebra is the complete Strang lecture series with recitation videos, problem sets and exams, and Single Variable Calculus is the Scholar edition built for self-study.
Picks for psychology, philosophy and politics
The Science of Well-Being is Yale's course on happiness, with practical challenges alongside the lectures, and Introduction to Psychology is twenty full Yale lectures covering the whole introductory syllabus. In philosophy, Oxford's General Philosophy is a complete first-year lecture course, openly licensed and transcribed; Critical Reasoning for Beginners is six lectures on spotting and testing arguments; and Yale's Death is a full course on a question everyone faces. Moral Foundations of Politics is a complete Yale political theory course from utilitarianism to democracy.
Picks for history, literature, finance and law
Yale's The American Revolution is twenty-five lectures with transcripts and readings, and Financial Markets is a full semester on finance with transcripts, readings and exams. Oxford's Approaching Shakespeare takes one play per lecture across thirty-two episodes. Two CS50 courses serve people outside technology: CS50's Introduction to Cybersecurity is a short security course for technical and non-technical learners alike, five weeks long, and CS50's Computer Science for Lawyers frames technology fundamentals around their legal implications.
Where to go after the picks
The picks are a short list, not a catalogue. For more in the same subjects, the computer science, Python, mathematics and psychology hubs list every verified course, including the free-to-audit HarvardX and MITx courses left out here. Several of the lecture-course picks from Yale and Oxford are also collected with others on the courses for seniors page, and the picks with a free credential appear under free certification courses.