Learn System
Design.
Practice the Interview.

Follow guided, interactive walkthroughs—then practice the same system in a mock interview with a whiteboard, voice or chat, and focused AI feedback.

Interview prompt library

NEWS FEEDCHATVIDEOPAYMENTSMAPSSEARCHURL SHORTENERFILE STORAGERATE LIMITERNOTIFICATIONSANALYTICSBOOKING

Everything you need to practice the full interview

A focused workspace for prompts, diagrams, conversation, and feedback—without switching tools.

Adaptive practice

AI-Assisted Interviews

Get real-time feedback on your architecture choices from an intelligent interviewer that adapts to your seniority level.

Think visually

Interactive Whiteboard

Draw system diagrams with an intuitive canvas. Create components, map data flows, and explain your design visually.

Interview library

Real-world Problems

Practice common interview-style prompts, from URL shorteners to globally distributed social networks.

Not ready for the mock? Learn the design first.

An AI tutor walks you through one system at a time. Watch the architecture take shape, make the decisions that matter, and ask questions whenever something does not click.

Step-by-step chapters
Chat or voice walkthroughs
Interactive design choices
Architecture built live

Live lesson

Design a notification system

Chapter 7 of 10

Architecture
Clients
API gateway
Notification service
Message queue
User preferences

Why place a queue after the API?

It absorbs traffic spikes and keeps notification delivery independent from the request path.

Design decision

How should we handle a sudden 10× notification spike?

AScale the API servers
✓Buffer work in a queue
CWrite directly to channels
Correct—now let’s trace delivery.

Ready for a focused
practice session?

Work through one prompt, explain your design, and review the feedback while it is still fresh.