# Observability
All Observability notes →1 — Uber
Covers Uber's published observability architecture and scaling decisions as a case study, cited from public engineering sources.
2 — Google
Covers Google's observability practices (Monarch, Dapper) and their influence on the broader industry's approach, cited from public sources.
3 — Meta
Covers Meta's internal observability and tracing infrastructure as described in public engineering writing.
4 — Netflix
Covers Netflix's observability and chaos engineering practices as described in public engineering writing.
5 — Amazon
Covers Amazon's operational excellence and observability practices as described in public engineering writing.
6 — Microsoft
Covers Microsoft's observability practices across Azure and first-party services as described in public engineering writing.
7 — Cloud Native CNCF Projects
Covers the CNCF observability landscape (OTel, Prometheus, and related projects) as a case study in open-source-driven standardization.
# System Design
All System Design notes →Chapter 18 — URL Shortener
The canonical warm-up case study — ID generation strategy and read-heavy caching are the whole design.
Chapter 19 — Distributed Cache (Case Study)
Designing a Redis/Memcached-like distributed cache end-to-end: sharding, eviction, and cache-coherence under concurrent writes.
Chapter 20 — Notification Platform
Fan-out to push, email, and SMS channels with per-channel rate limits, retries, and delivery-guarantee trade-offs.
Chapter 21 — Chat System
Real-time message delivery, presence, and ordering guarantees at the scale of a WhatsApp/Messenger-like system.
Chapter 22 — Video Streaming
Transcoding pipelines, adaptive bitrate delivery, and CDN placement for a YouTube/Netflix-like streaming platform.
Chapter 23 — News Feed
Fan-out-on-write vs. fan-out-on-read ranking delivery for a Facebook/Twitter-like feed at scale.
Chapter 24 — Collaborative Document Editor
Operational transforms and CRDTs for real-time multi-user editing in a Google Docs-like system.
Chapter 25 — Ride-Hailing Platform (Uber-like)
The end-to-end system: rider/driver matching, geospatial indexing, and surge pricing under real-time load.
Chapter 26 — Ride Matching Engine
The matching sub-problem in isolation — geospatial indexing (geohash/quadtree/H3) and the matching algorithm's latency budget.
Chapter 27 — Payment System
Idempotent transaction processing, ledger design, and exactly-once semantics where a bug means real money moves twice.
Chapter 28 — Distributed Lock Service
A ZooKeeper/etcd-like coordination service — leases, fencing tokens, and the split-brain failure mode that makes distributed locks genuinely hard.
Chapter 29 — Kubernetes Control Plane
etcd, the API server, schedulers, and controllers as a distributed-systems case study in their own right, not just an operator's tool.
Chapter 30 — GitHub-Scale Version Control
Git object storage, fork/merge at scale, and the read-heavy caching layer behind a GitHub-like hosting platform.
Chapter 31 — API Gateway
Routing, auth, rate limiting, and protocol translation as the single front door for a large service fleet.
Chapter 32 — Multi-Tenant SaaS Platform
Tenant isolation, noisy-neighbor containment, and per-tenant cost attribution for a shared-infrastructure SaaS product.
Chapter 33 — Recommendation Engine
Candidate generation, ranking, and the online/offline serving split behind a recommendation system at scale.
Chapter 34 — Feature Flag Platform
Low-latency flag evaluation, targeting rules, and safe rollout/rollback as a system design in its own right.
Chapter 35 — Secrets Manager
Envelope encryption, key rotation, and access-audit trails for a Vault/KMS-like secrets platform.
Chapter 36 — Distributed Scheduler
Cron-at-scale: exactly-once trigger semantics, backfill, and leader election for the scheduler itself.
Chapter 37 — CI/CD Platform
Build queueing, artifact caching, and progressive-delivery rollout as a system design for a GitHub Actions/Jenkins-like platform.
Chapter 38 — Object Storage (S3-like)
Erasure coding, durability math, and the eventually-consistent vs. strongly-consistent listing trade-off behind an S3-like store.
Chapter 39 — Cloud File Storage (Google Drive-like)
Chunked upload/sync, conflict resolution, and metadata-service design for a Drive/Dropbox-like file-sync system.
Chapter 40 — Distributed SQL Database
A Spanner/CockroachDB-like design combining consensus-replicated storage with a SQL query layer and distributed transactions.
Chapter 41 — Large-Scale AI Agent Platform
Serving thousands of concurrent LLM agent sessions — tool-call orchestration, memory/state, and cost-aware model routing at fleet scale.