In order to keep the stability and the deliverability across to all of our customers we implemented some restrictions/rules which are:


  • Load Balance of API
    • Currently we have 4 IPs which you can whitelist to access our https://api.sms.to. Those are:
      • 88.198.152.253
      • 88.198.168.146

      • 116.203.200.88

      • 116.203.125.205

  • Rate limit 30 per second on our API calls meaning:
    • if you try to hit any of our APIs in https://developers.sms.to/ and you pass the limit of 150 APIs per second, our system will return back the HTTP Code 429 Too Many requests.
    •  Response example:
      • {"success": false, "message": "Error 429 - Too many requests. You have been rate limited."}
  • Unsupported Content Type
    • In our API examples (https://developers.sms.to/#282792cb-e7e0-4dcd-91f2-34bf8cc74741) we specify what headers we need. One of them is the Content-Type. If this is not passed then we return back HTTP 415 Unsupported Media Type
    • Response example:
      • {"success": false, "message": "Missing or unsupported Content-Type value. Please use 'application/json'"}
  • Incorrect format
    • For every API we specify what we expect in the JSON Body to receive. If something doesn't match we return back HTTP 400 Bad Request.
    • Response example:
      • {"success": false, "message": "Invalid message or recipient details. Go to https://sms.to/docs for valid format"}
  • Unauthorized Access
    • In case your token on API fails due to an anti-flooding mechanism, we will return back HTTP 401 Unauthorized.
    • Response example:

      • {"success": false,"message": "Invalid API Key or Token","data": []}
  • Run out of balance
    • In case your account ran out of money, our anti-flooding mechanism will block your token and we will return back HTTP 402 Payment required.
    • Response example:

      • {"success": false, message:"Your balance is not enough to send message. Your current balance {current_balance}. Required {required_balance}. more to send messages"}