New ML & Java advanced lessons are live

Crack your computer science prep, one track at a time.

Structured, free lessons for DSA, OS, DBMS, networks, system design, web, ML and Java, with code you can run and interview questions that matter.

10+Learning tracks

90+In-depth lessons

100%Free & open source

Tracks

Everything you need, in one place

Pick a track and follow it end to end, or jump straight to the topic you need before an interview.

Complexity, arrays, lists, hashing, sorting and recursion with Python.

Scheduling, sync, memory, file systems.

SQL, normalisation, transactions.

From the link layer to TLS.

Scalability, caching, queues and a worked case study.

HTML, CSS, JS, React, Node and deployment.

NumPy to deep learning and MLOps.

JVM, streams, Spring Boot, interview Q&A.

Strategy, behavioural rounds, offers.

How it works

Follow the 6-month roadmap or choose a single track that fits your goal.

Short lessons with runnable code, tables and the pitfalls interviewers probe.

Practise in CodeArena, build portfolio projects, then rehearse real interview questions.

Free, open source and built with the community. Contributions are welcome.