Fast2SMS expects API Key to be included in all API requests to the server in a header for POST requests & in query parameters for GET requests.

Get your API Authorization Key from Fast2SMS Dev API section for FREE, which you need to add in each API request as follows:

For GET requests:

Include the API Key as a query parameter in the URL.

GET https://www.fast2sms.com/dev/wallet?authorization=YOUR_API_KEY

For POST requests:

Include the API Key in the request header.

POST authorization: YOUR_API_KEY

You must replace YOUR_API_KEY with your Fast2SMS account API Authorization Key.