Load tests: Jmeter vs K6

Hello all,

Today it’s the turn of Jmeter and K6 ! As always, remember to check your other options and see what better fits for your project.

Jmeter is a great and powerful tool, but depending on what you really need (something more lighter) then Jmeter might become an over complex, slow, hard to maintain tool.

Jmeter K6
In-built Protocols Support
  • HTTP
  • FTP
  • JDBC
  • SOAP
  • LDAP
  • TCP
  • JMS
  • SMTP
  • POP3
  • IMAP
  • HTTP 1.1
  • HTTP 2
  • WebSockets
Speed to write tests
  • Slow
  • Fast
Support of “Test as Code”
  • GUI oriented
  • Possibility to create scripts, but too complex and lack of documentation
  • Weak (Java)
  • Hard to maintain
  • Scripts oriented
  • JavaScript
  • Easier to maintain
Ramp-up Flexibility
  • Plugins available to be able to configure flexible load
  • Supports ramp-up phases and flexible load
Test Results Analyzing
  • Yes
  • Yes
Resources Consumption
  • Heavy to run tests with multiple users on a single machine, more memory consumption
  • Lightweight and doesn’t take up so much memory of your machine

Screenshot 2020-07-06 at 23.34.47

Easy to use with Version Control Systems
  • No
  • Yes
Number of Concurrent Users
  • Thousands, under restrictions
  • Thousands
Recording Functionality
  • Yes
  • No, but it allows to auto-generate a k6 script via an HAR file
Distributed Execution
  • Yes
  • Yes
Load Tests Monitoring
  • Add listeners, but consume more memory

Screenshot 2020-07-06 at 23.35.02

Jmeter is most used when:

  • You need to perform a complex load including different protocols
  • You can record scenarios
  • Robust support and training ecosystem
  • Require that a full scenario be written for every test
  • If you need to simulate specific load with some custom ramp-up patterns
  • If you just prefer UI desktop app for scripts creation, or you just do not know Javascript/YAML/JSON well enough


K6 solves some specific problems:

  • CLI tool with developer-friendly APIs.
  • You can use HAR files to generate record sessions
  • Checks and Thresholds – for goal-oriented, automation-friendly load testing
  • Open source, great support and documentation
  • Lightweight uses Javascript
  • Does not run in NodeJS and doesn’t run in a browser