Beginner 100 hours English Verified CertificateFREE
Our recommendation
Widely regarded as the best introduction to computer science anywhere. CS50 is demanding but superbly taught, taking you from C to Python, SQL and web basics through problem sets that genuinely teach you to think. Free to audit; the certificate is optional.
Good for: Beginners who want a rigorous grounding in how computing works, not just one language.
Less suitable if: You want a quick, gentle intro, or you only need one specific language fast.
You are ready to work through challenging problem sets
You value depth over speed
Consider something else if you…
You want a quick, gentle introduction
You only need one language for a specific task
You have very little time each week
Requirements: None — it starts from first principles, though it rewards persistence.
Realistic time: Around 100 hours. Most learners take a few months part-time; it is a real commitment.
About this course
CS50's Introduction to Computer Science is Harvard's legendary first course in programming, taught by David Malan. It's free to audit on edX; a verified certificate is optional and costs around $199.
What you'll learn
Think computationally and break down problems
Program in C and understand how memory works
Write Python for real tasks
Query data with SQL
Build a basic dynamic web app
Tackle and finish challenging problem sets
This course includes
100h
On-demand video
Yes
Certificate
English
Language
What it costs
Free to take on edX — all lectures and problem sets are open. Complete the problem sets and final project and Harvard issues a free CS50 certificate. edX also sells a separate verified certificate for around $199, but it is optional.
Comparison · LBS
Compare alternatives for CS50's Introduction to Computer Science
Same topic, different options. We surface the trade-offs others hide so you can pick the course that actually fits your time, budget, and goals.
CS50 offers a free certificate from Harvard once you finish the problem sets and final project; edX sells an optional paid verified certificate as well. CS50 is highly respected, but its real value is the skills and the work you produce — most people showcase the projects, with or without a paid certificate.
Last updated
Instructor
DJ
David J. Malan
edX instructor
4.5M learners8 courses4.9 instructor rating
David J. Malan is a Harvard professor whose energetic teaching turned CS50 into one of the most-taken courses in the world, on campus and online.
About this provider
ED
edX
Non-profit online learning platform founded by Harvard and MIT. 45M+ learners worldwide.
CS50x (this course) is the broad introduction to computer science, covering C, Python, SQL and JavaScript. CS50P is a separate course focused only on Python. You can take them in either order, and many people start here with CS50x.
Yes. Complete all the problem sets and the final project with a passing score and Harvard issues a free CS50 certificate. edX also sells a separate verified certificate (around $199), but it is optional.
Yes for a strong foundation. It is one of the most respected intro courses and teaches you to think, not just to code. Pair it with your own projects when job-hunting.
It is challenging but built for beginners. The difficulty is in the problem sets, which is also where most of the learning happens.
Most people take a few months of part-time study, roughly 100 hours. It depends a lot on your background and pace.
No. CS50x assumes no prior programming. Persistence matters more than background.
Rarely on its own. It builds strong fundamentals, but employers want to see projects and practical experience alongside it.