JMeter
Apache JMeter is an open-source Java application designed for load testing, performance testing, and functional testing of web applications and services. It simulates heavy loads on servers, networks, or objects to test their strength and analyze overall performance under different scenarios. It supports various protocols like HTTP, HTTPS, FTP, SOAP, REST, and JDBC.
Developers should learn JMeter when they need to ensure their applications can handle expected user traffic and identify performance bottlenecks before deployment. It is particularly useful for load testing web applications, APIs, and databases to validate scalability and reliability under stress. Use cases include testing e-commerce sites during peak sales, API performance validation, and database stress testing.