SYSTEM DESIGN · TRADING SYSTEMS · DSA

How real banking systems are built, explained by an engineer who builds them.

Deep, practical videos on fintech and investment-banking system design: order matching, trade lifecycle, risk, payments and low-latency architecture. Plus clear DSA and system design courses for engineers who want to level up.

// best bid / ask in constant time
Order bestBid() {
  return bids.peekFirst();   // O(1)
}

// cancel by id, no scan
void cancel(long orderId) {
  Order o = index.remove(orderId);
  o.level.unlink(o);         // O(1)
}

COURSES

Learn it properly, step by step

ABOUT

Hi, I'm [YOUR NAME].

I've spent [XX] years designing and building systems in investment banking and fintech, including [2–3 HIGHLIGHTS, e.g. trading platforms, risk engines, payments]. O(1) Club is where I share what I've learned, so engineers can understand how these systems really work, and get the roles they're aiming for.