CrackingWalnuts
New
41problems
System Design Interview Playbook
40-min walkthroughs with grading by level, follow-up Q&A, and one-pitch cheat sheets across every problem.
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90problems
Low-Level Design Interview Playbook
45-min code-in-sequence walkthroughs, whiteboard diagram mode, and grading rubric on every problem.
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145topics
Concurrency Section
Mental models, lock-free patterns, real-world bugs, and runnable examples in Go, Java, and Python.
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Pattern Pick
Binary Search
DSA TemplateBasic
ExploreDesign Blueprint
Video Conferencing
Low Level DesignAdvanced
ExploreScale Study
Design a News Aggregator
System DesignMedium
Deep divePacket Probe
Connection Pooling & Keep-Alive
Networking & ProtocolsIntermediate
ExploreStaff+ Prep
AI/ML System Design Interview
Staff+ InterviewExpert
ExploreKernel Dive
Virtual Memory & Address Spaces
Linux InternalsIntermediate
Deep dive
System Design: Maps Platform (Navigation, Routing, and Map Rendering)
Design a maps platform serving 1B daily users with real-time routing, tile rendering, traffic overlays, and offline navigation.
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System Design··79 min
Explore
DSA Templates
50Algorithm patterns & code templates
System Design
41End-to-end architecture problems
Low Level Design
90Design patterns & practical code
Key Technologies
59Deep dives into core tech
Infrastructure
35Production systems & operations
Networking & Protocols
51TCP, HTTP, TLS, DNS & more
Concurrency
145Threads, channels, async, locks in Java + Python + Go
Distributed Systems
38Consensus, replication & more
Linux Internals
84Kernel, networking & system calls
Cheat Sheets
24Quick reference cards for interviews
Recent Posts
System Design: GitHub (200M Repos, Git Object Storage, Sparse Trigram Code Search, Per-Job VM CI)
System Design
Apr 23, 2026 · 69 min
System Design: Online Auction (50K Bids/sec, Effectively-Once Settlement, Anti-Sniping)
System Design
Apr 17, 2026 · 83 min
System Design: Job Scheduler (10M Jobs/day, DAG Dependencies, Effectively-Once Execution)
System Design
Apr 15, 2026 · 61 min
Leadership
ManagerTech Debt Negotiation
“Quantify tech debt in business terms: hours lost per sprint, how often incidents happen, or how much deployment lead time has degraded”
Org Design
GrowthEngineering Hiring Pipeline
“Employee referrals consistently produce the highest-quality hires with the shortest time-to-close. Build a referral program with meaningful incentives ($5,000-10,000 bonuses are standard at tech companies) and make the process frictionless for referring employees”
800+Articles
27Interactive Tools
18Categories
6Learning Stages
Learning Path
Discover Today
Amazon SQS
AWS's managed message queue. No servers, no clusters, no headaches.
Object Storage & Data Lake
Stores unstructured data (files, images, logs, backups) as objects with metadata in flat namespaces
Consistent Hashing & Ring Algorithms
Adding or removing a server with modulo hashing (hash(key) % N) remaps nearly every key. With 100 servers, adding one server moves about 99% of your data. Consistent hashing remaps only 1/N of keys on average