Square Payments API Integration & Validation

I'm looking for a skilled developer to set up a PHP notification URL that can handle POST requests from the Square Payments API. The event details need to be captured and stored in PHP variables, including buyer name, email, product purchased, purchase amount, and date of purchase.

Key Requirements:
- Process POST requests from the Square Payments API.
- Save information to a PHP variable to enable me to capture to Database
- Validate incoming data to filter out certain $1 transactions.

A screenshot is attached showing the current system; which just ask for payment card details.

Ideal Candidates:
- Proficient in PHP and database management.
- Experienced with the Square Payments API.
- Able to implement data validation and filtering.