awesome-http-benchmark

I have not used it myself but colleagues of mine recommend k6: https://k6.io/open-source/ There is also a Github repository keeping track of all the load-testing tools out there: https://github.com/denji/awesome-http-benchmark You will probably find something that will fit your bill. I do not understand though why it is of any relevance what language the application is written in. Yes, Go and Rust indicate a certain speed and novelty but you can write fast applications with good UX in other programming languages too (and bad ones in Go and Rust).

Here is a good list — https://github.com/denji/awesome-http-benchmark It includes the good ones like Vegeta, Siege, Goad, Hey, Httpref, Gatling, among others.