k6 Cloud - Managed load testing service built on top of the popular open-source project k6.
Tsung - Tsung is an open-source multi-protocol distributed load testing tool.
OctoPerf - OctoPerf is a SaaS load testing solution, based on JMeter.
locust - An open source load testing tool written in Python.
WebLOAD - WebLOAD - The most flexible and cost effective software for enterprise load, stress and performance testing, integrated with DevOps processes. Click for details
Apache JMeter - Apache JMeter™.