Wordpress JSON API Development for Website Needed

NOW TAKING BIDS OVERVIEW: There are 2 systems at use here that need to keep track of customer accounts. A wordpress system is being used to get customer sign ups, purchase credit (in €10, €20 blocks) and to set up calls through a booking system. A phone system is being used to route calls, answer calls and direct customers to a phone based credit card charging system which will credit the account on Wordpress. It uses a PIN/Account number system to identify the customer. SCOPE: We require modifications to the WordPress system to provide the standard JSON API secured by signed API key (see authentication) and webhooks that will call JSON API's on the accounts system. [login to view URL] Webhook We require the following webhook to be called by WordPress on a configurable server /user/ Method "POST" Create or update a new customer in the accounting system Request body in JSON { "account_number": 19208, "pin": 2092, "first_name": "Test", "surname": "Test", "email": "example@[login to view URL]", "phone": "+44xxxxxxxxxxx", "account_type": "subscriber", "account_balance": "20000", "account_currency": "EUR" } Response codes 200 - Successful creation of account or update 500 - Server Error, retry 400 - Invalid entry - do not retry Events: User creation, user update, password or pin number update, purchases on WordPress should call the webhook. e.g. [login to view URL] Authentication: JSON Webtokens to be used for the WordPress side with a configurable expiry in the code. [login to view URL] Requests to the webhook must be signed using a configurable API key