Apache JMeter vs k6

Apache JMeter is a free, open-source Java application for testing functional behavior under load and measuring performance. It can simulate heavy workloads on servers, networks and other systems. Supported test types include HTTP and HTTPS, SOAP and REST, FTP, JDBC, LDAP, JMS, email protocols, TCP, Java objects, and native commands or shell scripts. Its test IDE can record plans from browsers or native applications, then help users build and debug them. JMeter provides command-line operation on Java-compatible systems and can generate dynamic HTML reports. It also supports remote testing, pluggable samplers and timers, scripting such as Groovy and BeanShell, and plugins for analysis and visualization. Third-party open-source libraries connect it to Maven, Gradle and Jenkins for continuous integration. JMeter works at the protocol level: it does not execute JavaScript in pages or render them as a browser does. It requires Java 8 or later. The project recommends command-line rather than GUI operation for load testing and advises caution with untrusted JMX files, which may execute code when opened.

k6 has no write-up on Specifiction yet; its figures are above.