Rate limit
Each API key may send up to 60 messages a minute. Above that the API answers 429 rate_limited with a Retry-After header in seconds. The limit is per key, so a second system on its own key has its own allowance. Need more? Contact us.
Credits
Sends are paid for with the same prepaid credits as campaigns: utility and authentication templates cost 1 credit, marketing templates cost 5. The debit happens before the send. If our messaging platform refuses the message, or WhatsApp later reports it failed, the credits come back automatically and the message shows FAILED.
When the balance cannot cover a send the API answers 402 insufficient_credits and nothing is sent. Top up in the app under Credits. The free trial sends that let you evaluate the app do not apply to the API: every API send is a paid send.