PayPal API Integration for PHP

We are in need of a skilled PHP developer with proven experience in integrating PayPal API. The primary task is to implement processing of one-time payments via various methods including Credit/Debit Cards and PayPal Balance.

Please note:
- We do NOT use a CMS (Wordpress, etc.).
- The user REMAINS on the page, inputs and outputs are done completely via fetch().
- No change of URL after success, error, abort - but only the corresponding response to the fetch API.
- It is only about the communication with the paypal API, all other processes, such as the provision of the order data and the logic depending on the feedback from Paypal are fully programmed and no further implementation is required.
- You are only responsible for the communication with the Paypal-API, we provide you with all the rest.

Key responsibilities:
- Implement PayPal API to process one-time payments
- Ensure acceptance of Credit/Debit Cards and PayPal Balance
- Maintain security and compliance with PayPal's standards

Ideal skills:
- Proficient in PHP
- Extensive experience with PayPal API
- Strong understanding of payment processing
- Prior experience in e-commerce solutions will be an advantage.

Looking forward to your bids.