All accounts are limited to sending 1 message per second. If this is too restrictive for you Contact Us to get an increase. If you are being rate limited the API will return status code 420 along with the following headers:

Retry-After
number

How long in seconds until you will be able to retry the request

SDKs

If you are using an official Byteflow SDK rate limiting is handled for you. All requests made are added to a queue and the requests are made when possible.