How to add Payumoney money gateway free to opencart 2.3

Hi,
Can some one suggest me the safe way how to add payumoney payment gateway to my store. I checked on the internet i find out that we need to pay $30 for extension and on some sites its free. One more thing i need to ask is there any better gateway than payumoney for small stores if so please name them and tell me how to add on store.


Thank you.