Hit vs. miss
Read a cold key and pay the ~106ms database round-trip. Read it again within its TTL and watch the same request return in ~5ms.
cacheflow — opening
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A distributed cache you can poke. Send reads and writes at a simulated cache and database, break things on purpose, and watch hits, misses, TTL expiry, and LRU eviction happen in real time.
Nothing in flight. Try a guided scenario below, or pick a key and send a request.
Read fetches a key. Write updates the database and invalidates its cached copy. Delete removes the record and its cached copy.
Failure is the feature
Static diagrams explain caching; they never let you feel it. Each scenario is one or two clicks away in the console above.
Read a cold key and pay the ~106ms database round-trip. Read it again within its TTL and watch the same request return in ~5ms.
Every entry carries a live countdown bar. When it hits zero the entry disappears, an event fires, and the next read silently misses.
Writes go to the database first, then delete the cached copy — the textbook answer to the hardest problem in computer science.
Four slots, six records. Fill a fifth key and the least-recently-used entry gets marked, then pushed out — visibly, with an event.
Under the hood
The simulation follows the same rules a production cache-aside deployment would — it just runs where you can see every move it makes.
Hits, misses, eviction, expiry, and invalidation are reproduced faithfully in the browser.
Every operation is planned as a pure sequence of steps before it animates — the same state always produces the same run.
Each event stores the full cache, database, and metrics state, so any moment can be re-opened and inspected after the fact.
Cache ~1ms, database ~90ms — explanatory constants, not benchmarks, chosen so the cost of a miss is impossible to ignore.
One client, one cache node, one database — the exact topology most systems start with. Replication and multi-node consistency are the natural next chapter.
Built by Abhishek Suman
Backend-minded engineering with interfaces that make complex systems easier to reason about.