Server performance

Cache/Load balance

HAProxy : C : load balancer

Free, fast and reliable solution offering high availability, load balancing, and proxying for TCP and HTTP-based applications

memcached : C : memory cache

Free & open source, high-performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by alleviating database load

Varnish : C : caching proxy

Web application accelerator also known as a caching HTTP reverse proxy

Test

Benchmark

bombardier : Go

Fast cross-platform HTTP benchmarking tool

WebPagetest : PHP/Python

Free website speed test from multiple locations around the globe using real browsers (IE and Chrome) and at real consumer connection speeds

wrk : C

Modern HTTP benchmarking tool capable of generating significant load when run on a single multi-core CPU

Load test

drill : Rust

HTTP load testing application written in Rust inspired by Ansible syntax

Vegeta : Go

Versatile HTTP load testing tool built out of a need to drill HTTP services with a constant request rate

See also

Further reading