How to test the API server for load?

Question

linux

Various HTTP API services that work with JSON are under development.
It is necessary to check how each service will behave under load individually and all together.
Let's say that you can "charge" with a set of JSON files and "shoot" (POST) them at high speed, changing them randomly or in a given order. Or specify parameters for GET requests and other methods.
It is necessary to find out what is the throughput of each and the entire system as a whole. Functionally, it would also be nice to check.
What tools would you recommend to use? Preferably open source and cross-platform.
In addition to the names of the tools, it is desirable to get links to slides / articles or documentation, for dummies.

Answer 1

ab || siege
https://habrahabr.ru/company/oleg-bunin/blog/319526/
At the beginning of the article there is a small description that gives some information about these tools