Step inside real systems.

Real architectures, running live in your browser. Watch them run, feel them strain, break them, and fix them.

Start breaking thingsToday's outage

Computed live in your browser, every tick. It's a model, not a video · see assumptions

LIVE· url-shortenersimulated · 1×
KEY GENERATION SERVICECheck CacheGet New KeyWrite/Read DBLog EventMobile App — client · mobileMobile Appclient · mobileWeb Browser — client · webWeb Browserclient · webLoad Balancer — lb · nginx ×20%Load Balancerlb · nginx ×2API Service — api · ×60%API Serviceapi · ×6Redis Cache — cache · redishit 0%Redis Cachecache · redisKGS Worker — worker0%KGS WorkerworkerKey Pool (SQL) — db · sql0%Key Pool (SQL)db · sqlURL Storage (Cassandra) — db · nosql0%URL Storage (Cassandra)db · nosqlAnalytics Stream (Kafka) — bus · kafka0 msgsAnalytics Stream (Kafka)bus · kafkaAnalytics Worker — worker · ×120%Analytics Workerworker · ×12
Live metrics:p99 —mserr —%—rpsretries —

Healthy at baseline. Your turn: kill the cache or send 10× traffic.

Break → Fix

Watch it fail. Then fix it and watch it recover.

Slow the database and retries pile up until every request times out. Every number is computed live from the diagram, never played back.

Try it in the simulator
ClientsAPIDatabasep99 4.2s
same shape the simulator draws · no backoff yet, so retries pile up
Outage replays

Relive the outages that made the news.

Real incidents, rebuilt from public postmortems. Scrub to the minute it tipped over and follow the chain reaction, one hop at a time.

Coming soon
UsersEdgeOrigin
real incidents, rebuilt from public postmortems — in progress
Walkthroughs

Every step, explained in plain words.

Guided walkthroughs follow one request, hop by hop, through the real diagram — no narration is invented, it's read straight from the same data the player runs on.

Take the walkthrough
  1. 01Write path: creating a short link
  2. 02Read path: a cache hit
  3. 03Read path: a cache miss
  4. 04When Redis dies
real walkthrough steps, URL Shortener System Design
Share

Every meltdown will be a link.

The URL will follow the simulation as you play, so a teammate can open the exact second the cache died.

Coming soon
simvora.dev/solutions/url-shortener?s=cache-outage&t=34

Pick a system. Break it.

Start with a healthy URL shortener. It takes about a minute to bring it down, and a little longer to learn why.

Start breaking thingsExplore all systems