Gatling.io is described as 'Gatling is a software designed for load and performance testing of web applications, APIs, and services. The software enables users to simulate user traffic and analyze the behavior and responsiveness of systems under various load conditions' and is a Benchmark tool in the os & utilities category. There are more than 25 alternatives to Gatling.io for a variety of platforms, including Windows, Linux, Web-based, Mac and SaaS apps. The best Gatling.io alternative is Apache JMeter, which is both free and Open Source. Other great apps like Gatling.io are locust, k6, wrk and Guardius.
Easy, Customizable, Scalable, Cloud ready, lot of resources, support and blogs available. Easier to customize than Gatling as it can be done with groovy vs Scala for Gatling.