API load testing is a powerful tool in your arsenal that gives you real, concrete data on what actually happens to your application servers under load. When used correctly, API load testing with industry-recognised load testing tools like JMeter and Gatling can accurately identify server-side performance bottlenecks in your application before go-live and allow you some time to fix issues before they even occur.
It’s worth noting, though, that API load testing isn’t the be-all and end-all of performance testing. In order to see a holistic view of application performance, it’s best to pair API load testing with some front-end performance testing.
Front-end performance testing is generally less technical than back-end performance testing, and there are some fantastic tools out there that make it a matter of entering your URL and looking at the recommendations. I’m a big fan of GTMetrix for this sort of quick analysis.
Another option is to complement API load testing scripts with browser-level load testing scripts. Tools such as Flood Element and Selenium can be used to create scripts that better measure the end user experience of your application. One solid strategy is to use API load testing to generate the majority of the load and then simultaneously run a single node of browser-level testing. This hybrid approach will give you the best of both worlds— back-end and front-end performance in a tidy, cost-effective package.
Load testing’s value is determined not by executing tests but by actually using the results to improve your application and inform your product roadmap. It’s best looked at as a continuous process that doesn’t end once a release goes live. Real load testing is an iterative and consistent way of measuring performance that is included in every development activity so that performance is baked into the project team’s definition of quality.