Rate limits▾

Rate limits

Per-key request limits, the headers that report them, and how to back off.

Limits are per API key, measured over a rolling 60-second window. They are separate from Meta's own messaging tier limits, which cap how many unique contacts you may start conversations with per day.

Endpoint group	Requests / minute
`POST /v1/messages`	600
`GET` on any resource	1200
`POST /v1/broadcasts`	60
`POST /v1/media`	120
Everything else	600

Headers

Header	Meaning
`X-RateLimit-Limit`	Ceiling for the current window
`X-RateLimit-Remaining`	Requests left in the window
`X-RateLimit-Reset`	Unix seconds at which the window resets
`Retry-After`	Seconds to wait — only present on a `429`

Backing off

Node

async function send(body: unknown, attempt = 0): Promise<Response> {
  const res = await fetch("https://api.sendport.tech/v1/messages", {
    method: "POST",
    headers: {
      Authorization: `Bearer ${process.env.SENDPORT_KEY}`,
      "Content-Type": "application/json",
      "Idempotency-Key": crypto.randomUUID(),
    },
    body: JSON.stringify(body),
  });

  if (res.status !== 429 || attempt >= 5) return res;

  const wait = Number(res.headers.get("retry-after") ?? 2 ** attempt);
  await new Promise((r) => setTimeout(r, wait * 1000));
  return send(body, attempt + 1);
}

Meta messaging tiers are a separate ceiling

A new number starts at 1,000 unique contacts per rolling 24 hours and climbs to 10K, 100K then unlimited as quality holds. Hitting it returns 422 with messaging_limit_reached, not 429.

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