When you receive a 429 - Too Many Requests, here is what you should do

{
  "errorCode": "CMN-301",    "message": "Request rate exceeded",    "errors": [      {        "errorCode": "CMN-301",        "message": "Request rate exceeded"      }    ]  }

Response code : 429????

Solution:

Check the usage plan under Applications Information section for your application.

While you hit 429 error, your application will stay in penalty interval for 60 seconds. During this time, donot make any calls.

You can avoid hitting 429 error by following usage plan RPM( Requests per Minute) data for APIs.