> ## Documentation Index
> Fetch the complete documentation index at: https://docs.nikiwa.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Rate Limits & Metering

> Per-key rate limits and how tool usage is metered.

## Rate limits

Each [developer key](/api-reference/authentication) has its own rate limit, measured in requests per minute. New keys are created with a default of 60 requests per minute. Exceeding it returns `429 Too Many Requests`.

<Tip>
  Rate limits are per key. If you run separate workloads, create a separate key for each, so one busy integration cannot starve another and you can revoke or measure them independently.
</Tip>

### Handling 429

Back off and retry. Simple exponential backoff (1s, then 2s, then 4s) is enough for most integrations. Spread bursts of calls out rather than firing them in parallel.

## Metering

Every tool call is metered and aggregated per key. For each key, Nikiwa tracks:

* **Current-period units**, the usage in the current billing period (`YYYYMM`).
* **Total calls** and **total units**, durable lifetime counters.
* **Per-tool breakdown**, calls and units grouped by tool name.

You can view all of this per key in the app. See [Usage & metering](/mcp/usage).

<Note>
  The Tools API and the [MCP server](/mcp/overview) are metered and rate-limited independently, each on its own per-key window.
</Note>