An AI interviewer that grades your system design like a real FAANG panel — diagram, scalability, and trade-offs. Walk in already knowing your weak spots.
No credit card · graded in seconds
“Strong fan-out-on-write choice. You missed the celebrity hot-key problem — address it.”
The loop that gets you ready
30+ real interview questions, from URL shortener to Netflix.
Drag-and-drop diagram + an AI interviewer asking follow-ups.
5 weighted dimensions, with the reasoning. Know exactly what to fix.
Post your score, challenge a friend, rise up the leaderboard.
Beat a hard problem? Get a clean, branded scorecard you can drop on LinkedIn or send to a friend in one tap.
Design Twitter's timeline
A scorecard worth sharing.
systemdesignlab.in · Can you beat it?
Daily streaks keep you coming back. The weekly leaderboard makes it competitive. Public profiles let you show off a portfolio of designs — a link worth putting on your résumé.
In-depth system design guides and case-study walkthroughs — free, no signup.
Free forever — all learning content plus a practice interview every week. Upgrade for unlimited access.
Free forever · no card required
90 days · Everything unlimited
Start your first AI-graded mock interview free. See your score in seconds.
No credit card · 7-day trial · 3 graded interviews