Algorithms

Pick one per limiter. Switching algorithms for the same namespace + identifier starts a new counter — they don’t share state.

Algorithm	Burst	Reset	Best for
`fixed-window`	Yes, at window edges	Hard wall	Simple quotas, caches, default
`sliding-window`	No	Continuous	Fair usage, precise caps
`token-bucket`	Yes, up to `limit`	Steady refill	APIs that can take a spike
`leaky-bucket`	Absorbs, then rejects	Steady leak	Smoothing bursty input

Default is fixed-window.

Fixed Window

Discrete windows. Fast. Can allow 2× at the boundary.

Exact timestamps. No cliff.

Start full. Spend tokens. They refill over the duration.

Fill the bucket. It leaks at a constant rate. Overflow rejects.