System Design · Hands-on Simulation

Redis Interactive
Playground

Learn Redis by building, breaking, and scaling distributed systems — not by reading about them. Every module below is a live simulation you control.

0Cache Hits Simulated
15Interactive Modules
0msBackend Required
01 · Fundamentals

What is Redis, really?

Six ideas, shown rather than described. Hover any card to watch it animate.

02 · Live CLI

Redis Terminal

A fully working fake redis-cli. Every command mutates real in-memory state and the keyspace panel updates instantly, including live TTL countdowns.

redis-cli 127.0.0.1:6379
redis>
Keyspace
Try: SET a 1, EXPIRE a 5, LPUSH q x y z, SADD s a b, HSET h f v, ZADD z 1 a 2 b, INCR c, KEYS *, FLUSHALL
03 · Playground

Data Structures Playground

Insert, delete, and search across every Redis type and watch the underlying structure animate.

04 · The Main Attraction

Cache Simulator

Tune the system, fire traffic, and watch requests race between client, Redis, and the database in real time.

Cache size (keys)40
Default TTL (s)20
DB latency (ms)120
Request rate (/s)4
Read / Write ratio90% read
Key space (uniques)25
Client
App servers
Redis
0 / 40 keys
DB
Source of truth
0%Cache Hit Ratio
0%Miss Ratio
0msAvg Latency
0%Memory Usage
0Evictions
0DB Queries
0Ops / sec
0Total Requests
05 · Policy Showdown

Cache Eviction Game

Identical workload, five policies. Fire the same request stream at each cache (capacity 8) and watch who survives.

06 · Topology

Master–Replica Simulator

Build a replication topology, write into the master, and watch replication packets flow. Drag nodes to rearrange.

07 · High Availability

Redis Sentinel

Three sentinels watch one master and two replicas. Crash the master and watch quorum voting trigger an automatic failover.

08 · Sharding

Redis Cluster Simulator

16384 hash slots, grouped into 32 visual bands across 4 master shards. Route keys, add nodes, and reshard live.

16,384 Hash Slots
09 · Messaging

Pub/Sub Simulator

Create channels and subscribers, then publish — every matching subscriber lights up as the message arrives.

Live Feed
10 · Durability

Persistence Visualizer

Compare No Persistence, RDB snapshots, and AOF logging under a crash-and-restart scenario.

Disk timeline:
11 · Coordination

Distributed Lock (Redlock)

Five independent Redis nodes. A client must acquire the lock on a majority (3 of 5) to hold it.

12 · Traffic & Chaos

Traffic Generator & Failure Lab

Blast the shared cluster with load, then break things on purpose and watch recovery.

Traffic Generator
Idle — 0 req/s sustained.
System Health
Failure Lab
13 · Observability

Live Dashboard

Every module above feeds this dashboard. Generate traffic or trigger a failure and watch it move.

14 · Real Systems

System Design Use Cases

Animated architecture diagrams for the Redis patterns you'll actually ship.

15 · Missions

Challenge Mode

Go back to the simulators above and hit these targets. Progress is tracked live.

16 · Knowledge Check

Redis Quiz

15 questions. Instant explanations. Let's see what stuck.