● Prep for interviews at Google · Meta · Amazon · Stripe

Do the interview
50 times before
the real one.

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.

Try a 5-minute drill — no signup

No credit card · graded in seconds

15+
Interview problems
40+
Learn modules
5-dim
AI scorecard
Design Twitter's timeline · 38:12 left
Client
API Gateway
Load Balancer
Fan-out svc
Redis cache
Cassandra
AI Scorecard8.2/10
Architecture8.5
Scalability8.0
Trade-offs7.0

“Strong fan-out-on-write choice. You missed the celebrity hot-key problem — address it.”

The loop that gets you ready

Practice → Get scored → Share → Repeat

01

Pick a problem

Real interview questions — Twitter, YouTube, URL shortener and more.

02

Design under the clock

Drag-and-drop diagram + an AI interviewer asking follow-ups.

03

Get a real scorecard

5 weighted dimensions, with the reasoning. Know exactly what to fix.

04

Share & climb

Post your score, challenge a friend, rise up the leaderboard.

Every score is a flex

Turn a good score into a share.

Beat a hard problem? Get a clean, branded scorecard you can drop on LinkedIn or send to a friend in one tap.

Share on LinkedIn Challenge a friend
System Design Lab

Design Twitter's timeline

8.2/10

A scorecard worth sharing.

⚡ Architecture 8.5📈 Scale 8.0

systemdesignlab.in · Can you beat it?

This week's leaderboardresets Sun
1Climb to the top9.1🔥
2Build a streak8.8🔥
3Your spot?—🔥
Make prep a habit

Streaks, leaderboards, and healthy rivalry.

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.

Free & public

Not ready to practice? Start by reading.

In-depth system design guides and case-study walkthroughs — free, no signup.

Your interview won't wait. Neither should you.

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No credit card · free during launch · unlimited 5-minute drills

· System Design Lab