Don’t just read system design.
Run it.
Interview in a live design room that pushes back. Step through the systems behind every concept, byte by byte. Everything on this site runs.
Do system design like it’s the real interview.
Not a solution video. A room that hands you the numbers and makes you commit.
- Pin the traffic, storage, and latency numbers first — then defend them.
- Watch the design break as load grows, and evolve it box by box.
- Make the real calls yourself — a wrong turn is a lesson, not a penalty.
- The full write-up unlocks at the end — the answer you should have given.
Don’t memorize the LSM tree. Run one.
Every core concept is a working machine. Step it forward, watch state change, break it on purpose.
- Byte-level state on screen at every step — nothing hand-waved.
- B-trees, consistent hashing, Raft, quorums, bloom filters, gossip…
- The same machines the interview rooms are built from.
A path, not a pile.
Ordered from bytes to distributed systems, prerequisites wired. You always know what to open next — and why.
Knowing the machines isn’t the same as passing the hour.
The part the concepts don’t teach: how to run the interview, how to size a system out loud, and which way to go at every fork you’ll be pushed on.
Method & drills
The spine you run in the room — requirements, targets, estimation, and how to answer “now scale it 10×.”
Design forks
SQL or NoSQL, push or pull, queue or not. Each one names the number that decides it, so you pick instead of hedge.
Interview rooms
The real thing, one call at a time — with the write-up you should have given waiting at the end.
Learned it in March. Keep it for the on-site in June.
Cards that resurface what you’re about to forget
Spaced repetition over everything you’ve run — tuned to the concepts you struggled with, not a generic deck.
Open the deck →Every term, defined where you learned it
Hover any term anywhere on the site. Each definition links back to the running system that taught it.
Browse the glossary →Free to learn. ₹999 covers a full prep cycle.
Foundation sims, two full interview rooms, the learning path.
Everything unlocked — one full interview-prep cycle.
Everything unlocked — good for a final-week sprint.
Your next system design interview is a room you’ve already been in.
Start free: every concept, and the first scenario of every interview room.