What examples of open source websites can you look at?

Question

PHP

I am designing a standard, uncomplicated social service with the ability to register, add, delete messages, etc. Interested in how the back-end is made in real projects, what is the logic of work there, and in general how everything works. Preferably in php. Where can I find and see such projects. I would like to receive links to such projects. because I basically didn't find anything.
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I would like to read something useful for creating social. services. because many nuances in such projects

Answer 1

github -> search -> blog (filtr:php)

Answer 2

Look at the structure here: sitecoder.blogspot.ru/p/blog-page_23.html