Locust is an open source performance/load testing tool for HTTP and other protocols. Its developer-friendly approach lets you define your tests in regular Python code. Locust tests can be run from command line or using its web-based UI

The Apache JMeter™ application is open source software, a 100% pure Java application designed to load test functional behavior and measure performance. It was originally designed for testing Web Applications but has since expanded to other test functions.

Orderly Ape is an open source (MIT) tool to run distributed and scalable k6 load tests on your own infrastructure using k6, kubernetes, grafana and influxdb.

Anyone on your team can load test with instant playback, an easy-to-use interface, and real browsers for reliable data.

Simplifies performance and load testing so that application delivery teams can take a standardized approach to ensure continuous performance, reliability, and scalability from development to production.

Loader.io is a free load testing service that allows you to stress test your web-apps & apis with thousands of concurrent connections.