Photo processing script for the site?

Question

Image processing

Good day to all!
So another question was born in my head, and I did not find a better place than here to post it.
In general, to the point: I'm wondering how sites that add various effects to photos work?
For example, there is an action for Photoshop, is it possible to somehow expose it in some kind of script and integrate it into the site?
If it is very difficult, I will not do it myself (because I am a hard humanist), but it is interesting for the general development.
Thanks for the replies.