For senior & staff backend and AI engineers
A prep plan weighted to your target role and company, then timed mock interviews with an AI interviewer that breaks your design and grades every round like a hiring committee would.
Free plan · 3 scenarios · 5 min each
Your architecture
Interviewer
Local batching works. Now: 50 sidecars spike at once against a single Redis key. Bound the global over-admission error for me — as a number.
You
Each sidecar leases 2% of the tenant budget per 100ms window, so worst case is N × lease…
The systems senior and staff loops actually ask you to design
How it works
Role, company type, level and interview date. Every loop weights skills differently.
Scenarios ordered by what your loop tests most, with focus areas you can see.
Timed three-round mocks, a graded report after each, and drills on what you missed.
Graded reports
Each round is scored against the scenario rubric. The report breaks your performance into scalability, reliability, cost and production readiness, shows exactly which mechanisms you named and which you missed, and gives you the checklist a strong candidate would cover.
Scorecard
Global Rate Limiter · 500k QPS
78
R1 Design
61
R2 Chaos
72
R3 Cost
Key sharding with salted hot keys
No fail-open policy during Redis partition
Your plan
AI Infra Engineer · AI lab · Staff
12 days left
Your roadmap
Your plan orders scenarios by what your target loop weights most. Finish a stop and the next one is queued. Weak concepts carry over between sessions, so the interviewer keeps pressing where you are soft.
Build my planRole guides
LLM gateways, inference serving, RAG and agent runtimes.
Correctness under contention, multi-region trade-offs, blast radius.
Solid scalable designs with clear data flow and failure handling.
Feature stores, retrieval, schedulers and serving infrastructure.
Why not just ChatGPT?
What one offer is worth
Months of prep
Comp figures are illustrative. Drag to match your offer.
3 months of SystemDrill Pro
$79
0.016%
of year-one pay — about 0.3 hours on the job. One leveled-up offer pays for it on day one.
Pricing
Free
$0
Everything you need to try a real loop.
Pro
$26/mo
$79 billed every 3 months
An interview simulator for system design loops at the senior and staff level. Tell us your target role, company type and level; we build a prep plan, then run timed three-round mock interviews where an AI interviewer pushes on your design and grades every round.
A chat window will discuss a design with you. It will not interview you. SystemDrill runs a fixed loop — design, failure injection, cost and edge cases — grades each round against a written rubric for that exact scenario, and tracks the concepts you keep missing across sessions.
Every scenario has a golden rubric: the mechanisms a strong answer must include, the trade-offs it should defend, and the failure modes an interviewer will test. The grader compares your answer to that rubric rather than inventing criteria on the fly.
Your answers, diagrams and uploaded resumes are processed by our third-party AI model provider to grade them, together with the scenario rubric. Avoid pasting confidential employer details. Transcripts and scores are stored in your account so you can review reports. The Privacy Policy explains this in full. Privacy Policy
AI Infrastructure Engineer, Senior Backend Engineer, Staff Backend Engineer and ML Platform Engineer, across Big Tech, AI labs, fintech, e-commerce and AI-native startups.
Yes. The free plan includes 3 scenarios, one 5-minute mock each. Pro unlocks the full catalog, retakes, and untimed interviews.