For Engineers

Level up your system design.

100+ curated problems. Real voice + whiteboard AI interviews. Honest feedback. Track your progress from L4 to Staff.

Real interview simulation

Not a quiz. Not a chatbot. You speak, draw, and think in real time — just like the actual interview. The AI listens, watches your whiteboard, and pushes back when you miss something.

Track your seniority progress

Every session is scored across 5 dimensions with a seniority verdict. See yourself move from L4 to L5 over weeks. Identify exactly which dimension is holding you back.

Company-tagged problems

Problems tagged by company (Google, Meta, Amazon, Uber, Stripe) and difficulty. Prep specifically for your target company and role. Know what's coming before you walk in.

Skill Progression

See yourself improve — session by session.

After every session you get a full breakdown: what you got right, what you missed, and a seniority verdict. Track your scores over time. Watch the gaps close.

Session 1 · Design URL Shortener

5.8L4

Session 4 · Design a Rate Limiter

6.9L4+

Session 9 · Design Twitter Feed

7.8L5
DesignLoop — Practice Session
Live
L5Design a distributed rate limiter
AI

Your token bucket handles single-node traffic well. |

ClientAPI GW[×50]Redis ClusterToken BucketService
You're speaking…

Coming Soon

Roadmap

Leaderboards

Rank against engineers globally by seniority tier. See where you stand at L5 or Staff.

Weekly Contests

Live system design challenges with real-time scoring. Compete, improve, get noticed.

Learning Paths

Curated problem sequences for each seniority jump. L4 → L5, L5 → Staff, and beyond.

Problem Library

100+ curated problems. 12 domains. Every company.

Problems tagged by company and difficulty (Easy → Expert). Used by engineers to prep and by teams to screen — the same problems, two different perspectives.

GoogleMetaAmazonNetflixUberStripe
Easy
Medium
Hard
Expert
12
Infrastructure
9
Messaging
8
Video & Media
11
Storage
7
Search
6
Collaboration
9
Analytics
5
Geo & Maps
8
ML Platforms
10
Social Feeds
8
Payments
7
Notifications

Seniority Calibration

The AI meets you at your level.

Set your target level and practice at the right depth. The AI automatically calibrates its rubric — L3 through Principal.

L3–L4Scaffolded hints, component fundamentals, validates core concepts
L5Deep trade-off probing, bottleneck analysis, failure mode coverage
Staff–PrincipalPeer-level dialogue, cross-org impact, maximum rigor expected

Sample questions by level

L3Junior

"Walk me through what a load balancer does before we scale this."

L4Mid-Level

"You've mentioned sharding. What's your strategy for hot partitions?"

L5Senior

"At 10M writes/day, your single Postgres node is a problem. How do you migrate with zero downtime?"

StaffStaff

"Other teams depend on this API. How do you version it while rolling out the new schema?"

PrincipalPrincipal

"The board wants 5-nines. Walk me through your runbook if the primary region fails during peak."

Ready to level up?

Start practicing for free. No credit card. 3 sessions/month on the free plan.

DesignLoop

The system design interview platform — built for engineers who want to go deeper.

By ThyncLabs · © 2026 · Early Access

System operational