Which API You Are Using to Fetch PHP Zip Codes

Hi Everyone!

I am new here, and yes, I am also new in the PHP world. Though I have worked in the WP industry but you can consider me a newbie PHP developer who has to explore lots of things. I am here to know which source do you use to fetch zip codes dataset into PHP? I found the following sources little helpful, but my mentor wants me to use any source other than GeoNames.

https://www.back4app.com/database/back4app/zip-codes-all-countries-in-the-world - This one is extracting data from GeoNames. It would be acceptable if I share it as an independent source? What are your views?
http://opensourcegis.org/ - I also found this source on the web because many of my seniors gave me a hint to find something with the GIS.

Do you think Google Maps API can assist me in this matter? All in all, I am confused. Please suggest me any authentic source. I am getting late to submit my tasks to my mentor.