Limit the rate to certain external requests?

Question

Client side optimization

Hello!
Let's say there is a multi-user engine, some parts of which can parse something from outside at the user's command. I would like to limit the speed of some external requests for some users.
UPD: I'm
interested in what server technologies this can be implemented with - is it possible to somehow limit certain requests through nginx or apache or Unix utilities? Or do you need to pass such requests through a self-written utility and cut off the speed there, at the system level? What is the best way to do this? Adding something is not a problem, I would like to understand the theory. The task, I think, is clear.
Now the architecture of the web application is being thought out, so in what interpreted language the engine will be written, I think it does not matter. Let's say for now in PHP.
For links on the topic, too, I will be very grateful.
Thank you.

Answer 1

The question is not very clear, I'll try to telepathize :)
You probably have gradations with a fixed speed:
user with role A - speed 100Kb
user with role B - speed 200Kb
If so, then you can use a set of local proxies, each of which will have a limit on download speed. Squid allows this, for example.