# Rate limits | Chersus

Documentation

# Rate limits

How Chersus throttles requests: per-account windows, the 429 response and Retry-After header, and how to raise a limit for your workload.

Last updated 2026-09-03

Rate limits scale with your tier, and they exist for one reason: to keep latency predictable for everyone on shared CPU infrastructure. We apply them per account, per minute, across all services. A chained run counts as one request.

## Reading the headers

Every response carries the current window state:

```
X-RateLimit-Limit: 600
X-RateLimit-Remaining: 598
X-RateLimit-Reset: 1725192000
```

## Handling 429

When the window is exhausted, Chersus returns `429` with a `Retry-After` header in seconds. Back off and retry once the window resets. Chersus never bills a request it rejects for rate limiting.

```
{
  "error": {
    "code": "rate_limited",
    "message": "Too many requests. Retry after 3 seconds."
  }
}
```

Queue work client-side with a token bucket rather than retrying in a tight loop. For batch jobs, chain services so one request does the work of several.

`rate_limited` sits alongside every other error in [errors](/en/docs/errors/), which covers what bills and what does not.

## Retries and idempotency

Send an `Idempotency-Key` header with a unique value per logical request whenever a retry is possible. Chersus keeps the key and the resulting `trace_id` for 24 hours, with no content. A repeat with the same key returns `status: "duplicate"` and the original `trace_id`. It runs nothing, bills nothing, and your client keeps the first response.

## Other limits

A single run accepts at most 100,000 characters of input. The validator rejects larger inputs before anything runs or bills. Region is an account setting, not a request field; the audit trace records the region that served each run.

## Raising limits

Limits rise automatically with your monthly character tier. On the Corporate or Volume tier and need dedicated throughput, or a single-tenant European cluster? Ask about reserved capacity.