Rate limits, restrictions and API errors

Rate limiting

Each API key is limited to a number of requests per minute, according to your plan: Starter 60, Business 180, Pro 500, Enterprise 1,200 requests/minute. Beyond that, the API returns a 429 Too Many Requests error with a Retry-After header (60 seconds) and the X-RateLimit-Limit, X-RateLimit-Remaining and X-RateLimit-Reset headers. High volume accounts may request an increase in this limit. For bulk sends, the bulk endpoint accepts up to 10,000 messages per request.

Common HTTP response codes

• 200 OK — request processed successfully
• 400 Bad Request — missing or malformed parameter (e.g. invalid number)
• 401 Unauthorized — API key missing or invalid
• 402 Payment Required — insufficient balance
• 429 Too Many Requests — rate limit exceeded
• 500 Internal Server Error — platform side error, contact support with the time of the request and the returned error.code

Best practices

• Implement retry logic with exponential backoff on errors 429 and 500
• Systematically log the returned message_id to facilitate any future diagnosis
• Use sandbox mode to test your integration without consuming real credits or sending real messages