substation · rate limiter
POST /api/hit

Two rate limiters, actually running, hit them yourself.

This isn't a diagram of a rate limiter. It's a live token bucket and a live sliding window, both running server-side right now, both a real HTTP request away. Fire requests from the page, or from your own terminal with the curl below — same backend, same state, same result either way.

First piece of Substation — the quiet load-bearing infrastructure most systems run on, made visible instead of hidden. More pieces (a KV store, a job queue, an event pipeline) are on the way.

Token Bucket refills continuously
–/ – tokens
capacity
10
refill / sec
2
Sliding Window rolling count
–/ – in window
limit
10
window (ms)
5000
Hit it from your own terminal
curl -X POST https://systems.karangandhi.dev/api/hit \
  -H "Content-Type: application/json" \
  -d '{"algo":"tokenBucket"}'
Both limiters share one live instance across every visitor watching this page right now — you and a stranger elsewhere are pulling from the same bucket and the same window. That's deliberate: it's what makes this a real system under contention, not a private sandbox. Green ticks are allowed, short red ticks are denied.