Picking an API testing tool for a Rails app usually means choosing between a lot of options that each solve a different part of the problem. This comparison of the best automation testing tools looks at 12 of them by use case: CI/CD automation, manual exploration, performance, security and SOAP. It covers Keploy, Karate, Postman/Newman, Bruno, Insomnia, k6, JMeter, OWASP ZAP and SoapUI, and includes a comparison table and a short guide for choosing a tool. Since these tools work over HTTP and don’t depend on the language, they apply to Rails and Sinatra APIs as well.