CrackingWalnuts
Today's Lineup
Pattern Pick
Fast & Slow Pointers
DSA TemplateBasic
ExploreDesign Blueprint
File Storage (Dropbox)
Low Level DesignAdvanced
ExploreScale Study
Design an Ad Click Aggregator
System DesignMedium
Deep divePacket Probe
REST vs GraphQL vs gRPC
Networking & ProtocolsIntermediate
ExploreStaff+ Prep
Cross-Team Dependency Management
Staff+ InterviewAdvanced
ExploreKernel Dive
PAM: Pluggable Authentication Modules
Linux InternalsIntermediate
Deep dive
Explore
DSA Templates
35Algorithm patterns & code templates
System Design
39End-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
Distributed Systems
38Consensus, replication & more
Linux Internals
84Kernel, networking & system calls
Cheat Sheets
24Quick reference cards for interviews
Recent Posts
System Design: LeetCode (Code Sandbox, Container Isolation, Real-Time Contests)
System Design
Apr 12, 2026 · 68 min
System Design: URL Shortener (10B Short URLs, 100K Redirects/sec)
System Design
Apr 11, 2026 · 42 min
System Design: Ad Click Aggregator (10B Clicks/day, Lambda Architecture, Fraud Detection)
System DesignData Engineering
Apr 10, 2026 · 70 min
Leadership
DirectorMigration Program Management
“The last 20% of any migration contains 80% of the pain. Budget and staff for it explicitly, or it will drag on for years as a zombie project”
Org Design
GrowthRemote-First Org Design
“Remote-first is not the same as remote-friendly. Remote-first means every process, meeting, and decision is designed for distributed participants by default. If your office employees have an information advantage over remote ones, you're remote-friendly at best”
530+Articles
27Interactive Tools
16Categories
6Learning Stages
Learning Path
Discover Today
InfluxDB
The purpose-built time series database that owns the IoT and metrics space
Replication & Consistency
Copies data across multiple nodes for fault tolerance and read scalability
Streaming Quantiles: T-Digest & DDSketch
You cannot average percentiles. The P99 of shard A and the P99 of shard B does not give you the global P99. This is the fundamental reason streaming quantile sketches exist