locust is described as 'An open source load testing tool written in Python. Locust allows you to define user behaviour with Python code, and swarm your system with millions of simultaneous users' and is an app. There are more than 25 alternatives to locust for a variety of platforms, including Windows, Linux, Mac, Online / Web-based and Self-Hosted solutions. The best alternative is Apache JMeter, which is both free and Open Source. Other great apps like locust are hey, Loader.io, YandexTank and k6.
locust is mainly a Benchmark Tool but alternatives to it may also be Web Servers. Filter by these if you want a narrower list of alternatives or looking for a specific functionality of locust.
Apache JMeter is an open source Java application, designed to load test functional behavior and measure performance. Originally designed for testing Web Applications, it has since expanded to other test functions as well.
ab is a tool for benchmarking your web server. It is designed to give you an impression of how your current web server installation performs. This especially shows you how many requests per second your web server installation is capable of serving.