Interactive System Design Simulations

All 21 simulations are free and run in your browser — no account needed. Use them alongside the guide to turn abstract tradeoffs into hands-on intuition.

• Capacity Estimator — Dial up users and request patterns — watch QPS, storage, and bandwidth derive themselves.
• CAP Theorem Simulator — Visualise consistency vs. availability under network partition.
• Load Balancer Simulator — Compare round-robin, least-connections, and random routing — and kill servers to test fault tolerance.
• Database Sharding Simulator — Write records and watch them land on shards — then see why rebalancing is the hard part.
• Forward & Reverse Proxy Simulator — Route requests through a forward or reverse proxy and watch what each side can and cannot see.
• CDN (Content Delivery Network) Simulator — See how edge caching reduces latency and origin load.
• API Gateway Simulator — Route requests through a gateway and watch authentication, rate limiting, and routing enforce policy in sequence.
• Service Discovery Simulator — Kill service instances and watch the registry update — then compare client-side vs server-side discovery.
• Circuit Breaker Simulator — Trip the breaker with auto-send, watch half-open recovery, and understand cascading failure protection.
• Caching Strategies Simulator — See LRU eviction in action — watch which cache entry gets bumped on every access.
• Database Index Explorer — Visualise how B-tree indexes speed up reads at the cost of writes.
• Saga Pattern Simulator — Trigger a failure mid-transaction and watch compensating transactions roll the saga back — in orchestration or choreography mode.
• Message Queue Simulator — Drop messages into a queue, watch consumers race to process them, and break delivery guarantees to see why idempotency matters.
• Database Replication Simulator — Watch leader-follower replication lag and failover happen live.
• Rate Limiter Simulator — Send traffic bursts and watch the token bucket accept or drop requests in real time.
• Bloom Filter Simulator — See how probabilistic membership testing avoids expensive lookups.
• LSM Tree (Log-Structured Merge Tree) Simulator — Understand how write-optimised storage engines like RocksDB work.
• Gossip Protocol Simulator — Step through or auto-run gossip rounds and watch infection spread across the cluster.
• Distributed Consensus Simulator — Trigger elections, partition nodes, and watch a cluster agree — or fail to — in real time.
• Object Storage Simulator — Upload a file, watch it chunk and replicate across storage nodes, then kill a node to see durability hold.
• Consistent Hashing Ring Simulator — Add and remove nodes to see minimal key remapping in action.