DSA + Data Science + hands-on projects
The coding mentor you wish you had.
Build a daily habit of solving real DSA and Data Science problems. A Socratic AI mentor guides you through each one - and runs your code against real tests.
440 DSA + 631 Data Science problems · 100 AI messages free every week · no credit card
A mentor that asks, not answers.
Get stuck and it doesn't hand you the solution - it asks the question that gets you there yourself. The way a good senior engineer would.
One question. Day done.
The daily ritual is simple: open the roadmap, solve at least one problem, keep the streak alive.
Pick a topic
Open the roadmap and choose a topic, or pick up where you left off. No diagnostic, no setup - you're solving in seconds.
Solve real problems
Real coding problems, ordered into a curriculum instead of a random pile. Write code and run it against real test cases.
Never get stuck alone
A Socratic AI mentor nudges you toward the answer instead of handing it over. The moment you're stuck, it's already there.
Not Duolingo. Not LeetCode. Not Coursera.
Open-ended sessions on real problems, a guided path, and a mentor who actually teaches. We took the good parts and left the rest.
A curated curriculum, not a grind
440 DSA and 631 Data Science problems, ordered step by step from fundamentals up. You always know what to do next - unlike a wall of unsorted problems.
A mentor, not an answer key
The AI is Socratic by default: it asks before it explains, offers hints before solutions, and reasons through test failures with you. Closer to a senior engineer than a chatbot.
Real code, real tests
Run Python in your browser for free. Upgrade for multi-language execution against full test suites - the same way your code gets judged for real.
Progress that compounds
Every problem solved fills in your roadmap and feeds your streak. Show up daily; watch consistency turn into mastery.
Questions, answered.
Is Onlearn free?
Yes. All content, in-browser code execution, and your full progress and streak are free forever. The AI mentor is metered at 100 messages a week on the free plan; upgrade for unlimited.
How is this different from LeetCode?
LeetCode is a wall of problems you grind alone. Onlearn is a curated curriculum - problems ordered into a roadmap - with a Socratic AI mentor on every single one. You build a habit, not just a solved-count.
What does the AI mentor actually do?
It guides you Socratically: asking questions, offering hints before solutions, reviewing your code, and reasoning about test failures with you. It's there to help you understand, not to hand you the answer.
What can I practice?
Two tracks at launch: Data Structures & Algorithms (440 problems) and Data Science (631 problems), ordered from fundamentals to advanced. More tracks are on the way.
Which languages can I use?
Python runs in your browser for free. A paid plan unlocks multi-language code execution against full test suites for the DSA track.
Do I need a credit card to start?
No. Sign up and start solving immediately. You only pay when you choose to upgrade for unlimited AI mentoring and multi-language execution.
Start the habit today.
Free to start - 100 AI messages every week, all content unlocked. Upgrade anytime for unlimited mentoring and multi-language execution.
no credit card · cancel anytime