Scalability Toolkit
The numbers behind systems that hold up under load — caching, capacity, and the metrics worth actually tracking. All run entirely in your browser.
How these fit together
Cache Hit Ratio Calculator turns raw request and hit counts into the one number that tells you whether a cache is actually earning its keep — hit rate and miss rate, with a visual breakdown and reference ranges for CDN and application caches so a given percentage means something instead of floating in isolation. Database Index Cost Estimator puts a number on the other classic scalability trade-off — simulating whether an index's read savings (a full table scan versus a B-tree lookup) outweigh the write overhead it adds to every insert and update, in comparable operation counts instead of a guess. Throughput Calculator answers the question those first two feed into — given a target requests/sec, a latency, and an instance count, exactly how much headroom the system has and how many instances a given load actually needs, via Little's Law.
Cache Hit Ratio Calculator
Calculate hit rate and miss rate from total requests and cache hits.
Database Index Cost Estimator
Simulate whether an index's read savings outweigh its write overhead, in comparable operation counts.
Throughput Calculator
Estimate system capacity from requests/sec, latency, and instance count, via Little's Law.