There are many free polygon RPC services like Infura and Moralis which I recommend using if you have a small personal project, but with projects of a larger scale, these services can get quite expensive and unreliable

In this tutorial, I will show you how to set up your own personal RPC endpoint by deploying a Polygon full node. This includes both an HTTP RPC endpoint and a websocket endpoint

Keep in mind this will require renting/setting up a server which is going to cost monthly to maintain, so if you’re just starting out with polygon development I would suggest using one of the free services I’ve listed

Take a look at the official node deployment guide for hardware requirements and additional information. As of October 2021, you need more than the 650 GB specified and I would recommend a 2 TB disk (make sure it is SSD)