← Frontend System Design
The RADIO mock interview

Pass the interview before the interview.

Forty minutes on the clock, five stages, and the same calls you'd have to make in a real room. Every decision is scored the moment you commit — and every option explains itself afterwards, so each run makes you sharper than the last.

The case files — pick your interview
IV
Your interviewer
“I've booked 40 minutes for us. Let's design a news feed — where would you start?”
R
Requirements
Ask sharp questions
A
Architecture
Draw the system
D
Data model
Shape the store
I
Interface
Define the API
O
Optimizations
Spend your budget
Medium · ~40 min · 25 points · no signup, instant feedback
Short on time? Drill one stage:
What you're playing for
Keep drilling
under 15 pts
The lessons will fill the gaps
Solid
15–20.75 pts
You'd hold your own in the room
Strong signal
21.25+ pts
You'd impress a real interviewer