theonsite.dev is a system design interview practice platform with an interactive whiteboard canvas, curated real interview questions, session recordings, and reference answer keys.
1 free beginner challenge — no credit card required
Choose from 27 real interview questions asked at Google, Meta, Stripe, and more.
Architect your solution on an Excalidraw canvas with a real countdown timer. No peeking.
Reveal a detailed answer key side-by-side with your diagram. See exactly what you missed.
Draw your design under real interview conditions, then compare to a reference answer
Spot exactly what you missed — load balancer, read replicas, async pipelines
From beginner-friendly to the hardest questions asked at FAANG
A complete practice environment, not just flashcards
Design systems on a Excalidraw-style infinite canvas. Draw components, arrows, and annotations just like a real whiteboard interview.
Record your practice sessions and review them later to spot gaps in your reasoning and improve your communication.
After your attempt, reveal a detailed answer key written by engineers who've passed interviews at Google, Meta, Amazon, and more.
Start with approachable beginner challenges, then level up to the complex distributed systems problems asked at top companies.
Start free, upgrade when you're ready
$8.25/mo · $19/mo
Join engineers who are practicing with real system design challenges. Start free today.
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