Design a Distributed Counter — From 100 to 100M Updates per Second
Distributed counter at every scale. Postgres single-row up to ~10k updates/sec. Redis sharded counters up to ~1M. Async aggregation patterns for billions.
System Design
Design a Content Moderation System in 2026 — Human + AI in the Loop
End-to-end content moderation design. Automated rules, ML / LLM classification, human review queues, appeals, and the patterns from real platforms.
Designing a Multi-Region SaaS in 2026 — Patterns That Actually Work
Multi-region patterns: per-tenant region pinning, read replicas everywhere, write to home region, eventual consistency on the global plane, and the operational realities.
Design a Voice Chat System Like Discord — System Design Walkthrough
End-to-end design for voice chat: WebRTC, SFU vs MCU, signaling, presence, room state, and the operational realities of running voice at scale.
Design a Real-Time Bidding System — Sub-100ms Latency at Scale
RTB system design. Latency budget breakdown, candidate generation, ranking, fraud, billing, and the operational realities of a sub-100ms decisioning pipeline.
Distributed Locks in 2026 — Redis, Postgres, Zookeeper
Designing distributed locks. Redlock vs Redis SET NX, Postgres advisory locks, ZooKeeper / etcd, fencing tokens, and the patterns that prevent split-brain.
Design a CDN — Edge Caching at Internet Scale in 2026
End-to-end CDN design. Anycast routing, edge / regional / origin tiers, cache hierarchy, purge propagation, and the operational realities.
Design a Newsletter / Email-at-Scale System — 2026 Patterns
End-to-end design for sending newsletters / transactional email at scale. Sender reputation, bounce / complaint handling, suppression lists, throttling per provider, and the patterns from real ESPs.
Design a Distributed Cache — Memcached Successor Patterns in 2026
End-to-end design for a distributed cache. Consistent hashing, replication, eviction policies, hot keys, and the operational realities.
Design a Leaderboard / Counter System at Scale — 2026 Patterns
Leaderboards and live counters at scale. Redis sorted sets, counter sharding for hot keys, eventual consistency tradeoffs, and the production realities.