Rate limits

Limits apply per API key, over a sliding one-minute window:

Endpoint	Requests per minute
`POST /v1/sms/send`	60
`GET /v1/sms/status/{message_id}` and `GET /v1/sms/batches/{batch_id}` (shared)	120
`GET /v1/sms/balance`	30

A request counts towards the limit even if it then fails validation.

Headers

Every response includes:

Header	Meaning
`X-RateLimit-Limit`	Requests allowed per window for this endpoint
`X-RateLimit-Remaining`	Requests left in the current window
`X-RateLimit-Reset`	Unix time (seconds) when the next request will be accepted

When you go over the limit you get 429 rate_limit_exceeded with a Retry-After header (seconds to wait).

Send lists, not loops. One request can carry up to 10,000 numbers — far better than thousands of single sends.
Use webhooks instead of polling /status. Delivery reports come to you.
On 429, wait for Retry-After and retry. Don't retry immediately in a tight loop.
If a system needs more capacity, give it its own key — limits are per key.