It requires good amount of time to locate the PayPal REST SDKs download Github Location

We will make it easier for you.

Java

Download from here https://github.com/paypal/PayPal-Java-SDK

.NET

Download from here https://paypal.github.io/PayPal-NET-SDK/

Node

Download from here  https://paypal.github.io/PayPal-node-SDK/

PHP

Download from here https://paypal.github.io/PayPal-PHP-SDK/

Python

Download from here https://github.com/paypal/PayPal-Python-SDK

Ruby

Download from here https://github.com/paypal/PayPal-Ruby-SDK