Rate limits - Symmetry Docs

The CBS API reports your usage on every response and enforces a calculation cap on trial keys.

Limit-status headers

Every API response includes these headers:

Header	Meaning
`X-Pcc-Api-Calc-Limit`	Calculations allowed for the key (`0` means unlimited).
`X-Pcc-Api-Calc-Remaining`	Calculations remaining (`N/A` when unlimited).
`X-Pcc-Api-Exp-Date`	The key’s expiration date.

Monitor X-Pcc-Api-Calc-Remaining to avoid interruptions as you approach the cap.

When you hit the limit

The cap is checked on calculation requests (POST). When a trial key exceeds its limit, the API returns HTTP 401 Unauthorized with:

{ "message": "API rate limit has been exceeded." }

The calculation cap applies to trial keys. Standard (paid) keys are not blocked by this limit. The headers still report status, but production usage isn’t capped by this mechanism. Confirm your key’s limits with Symmetry.

For how keys are authenticated, see Authentication model.

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​Limit-status headers

​When you hit the limit

Limit-status headers

When you hit the limit