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Data structures and algorithms, learned through real product engineering.
Every concept starts as a task at Kestrel, a fictional global tech company, and ends with you explaining the pattern in your own words. Built for placements and interviews, fundamentals from zero, and competitive programming.
Everyone who joins while DSA Mastery is free keeps System Design Mastery and DSA Mastery free for life, with AI features on fair-use daily credits.
Founding access belongs to the account with the email you join with; sign in with that email to keep it. It covers every feature of both courses for as long as they run. AI features use daily fair-use credits, which may change with running costs. The free period ends on a date announced in advance, and everyone who joins before then is included. We use your email only for DSA Mastery and course updates.
Six beats, the same in every lesson and lecture. You meet the problem before the solution, measure a first attempt at production scale, and leave able to explain the idea, not just recall it.
Problems are set across Kestrel's product lines: Shop, Rides, Stream, Pay, Freight, Search, Chat, Maps and more. A small team carries each lesson, with short workplace dialogue that serves the explanation.
def busiest_stretch(plays: list[int], k: int) -> int: total = sum(plays[:k]) best = total for r in range(k, len(plays)): total += plays[r] - plays[r - k] # one joins, one leaves best = max(best, total) return bestHourly play starts on Kestrel Stream, in thousands. Find the busiest three-hour stretch.
The window sum is 13. It slides right: 4 leaves and 1 joins. What is the new sum?
Each world is a Kestrel division with its own map of roads, concept stops, checkpoints, gates and bosses. A problem solved anywhere counts in every world that contains it, and switching worlds is free.
Learn, practise and revise in one place. AI plans, curates and coaches, while problem selection stays rule-based and the solutions stay yours.
Kestrel's product lines are the systems System Design Mastery teaches. Each data structure links to the real system that depends on it, and both courses share your sign-in, profile, streak and XP.
We are building and testing it now and aim to open in early 2027, with the Foundations world complete and more worlds arriving in weekly waves. Everyone on the waitlist hears first.
Learning stays free for everyone: lessons, lectures, traces, games and quizzes. Some practice features may become paid after the free period. Founding members keep every feature of both courses free for life.
AI features run on daily credits shared across both courses. Founding members get them every day, with a daily limit that keeps the service sustainable for everyone.
No. DSA Mastery starts from zero. Both courses share one account, one profile and one XP total, and lessons link to each other where a data structure powers a real system.
No. Kestrel is fictional, so problems never use real company names. Company-specific prep shows only topics candidates have publicly reported, with sources, and makes no claim of insider information.