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SDE Interview
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// deep dives into system design,
// tech stacks & DDIA concepts
// for engineers leveling up
Featured Article
Loop Engineering
An agent is a loop: call the model, act, observe, repeat. Loop engineering is the discipline of designing that control flow — stopping conditions, budgets, in-loop verification, recovery from doom loops, and the topology that fits the task.
Results & Reviews
"After two system design mocks, the real Google onsite felt like a replay. He flagged the exact gaps the interviewers later probed — I walked in knowing what they wanted."
"My resume went from 2 callbacks to 11 in three weeks. The bullet rewrites turned vague tasks into real impact — recruiters finally noticed."
"The system design mock was honestly harder than my actual Amazon loop. By the real thing I was calm, structured, and got the offer."
"I kept bombing behavioral rounds and didn't know why. One session reframed my stories with actual signal and I passed at Microsoft."
"Jumped from a non-FAANG role to a senior position. The feedback was brutally specific — no fluff, just the gaps I needed to close."
"As a new grad I had no idea what 'good' looked like. The resume rewrite plus two mocks got me three offers, including my top choice."
Categories
E-commerce, video streaming, ride-share, URL shortener and more. Real interview questions solved end-to-end.
21 articlesDeep dives into the technologies powering modern systems — databases, caches, queues, and APIs compared.
23 articlesCondensed notes and takeaways from Designing Data-Intensive Applications — the SDE interview bible.
12 articlesAI coding tools, prompt engineering, agents, building on LLM APIs, and what it all means for interviews.
11 articles16 tutoring sessions of algorithm patterns — binary search to DP and randomization, with Java solutions to the classics.
1 articleSystem Design Breakdowns
Design ChatGPT — an AI Chat Assistant
Streaming (SSE), the GPU inference layer, an LLM gateway, memory & RAG, and the cost tradeoffs.
System DesignDesign a RAG System at Scale
Chunking, the vector index (ANN), hybrid retrieval, reranking, and grounded answers with citations.
System DesignDesign an E-commerce Platform
Product catalog, cart, inventory, payment processing, and order management at scale.
System DesignDesign a Map Web App
Geo-indexing, tile rendering, routing algorithms, and location search at scale.
System DesignDesign a Video Streaming Platform
CDN strategy, encoding pipeline, chunked delivery, and handling millions of concurrent viewers.
System DesignDesign a Chat App
WebSockets, message fan-out, presence indicators, and real-time delivery at scale.
System DesignDesign a Ride-share App
Geo-indexing, driver matching, surge pricing, and trip state machine design.
System DesignDesign a URL Shortener
Hash collision handling, redirect latency, analytics tracking, and custom slugs.
System DesignDesign a Hotel Booking App
Inventory locking, double-booking prevention, search ranking, and payment flows.