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Load Testing Your API's - How to make sure you are Ready?! - [Part 1]

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    Bruno da Silva Valenga

This article will talk about how to load test your APIs. Load testing your APIs by simulating heavy traffic can help make sure that your API will be able to handle anything thrown at it!

Load testing your API means simulating heavy traffic coming into your API, and it can help you make sure that it is able to handle anything that is thrown at it. Start by identifying the different types of traffic that come in on an average day. The more specific you get about what type of traffic, the better, such as common business hours or if there are any seasonal variations.


When load testing your API, you first need to create a model for how the API will act while functioning normally. This is also called a baseline.


Create a model for how much traffic each type will produce. For example, you can make a model that says that 20% of all traffic will be from people accessing their accounts, 40% from people who are checking out items in their shopping cart and 60% from people adding items to their cart for purchase. Once you have created these models, you can establish at what point the API will fail. In other words, you have to know when your system can no longer handle or deal with any more incoming requests.


You also want to identify what type of response time your API should meet for individual requests. For example, if your API is designed for fast responses, then limitations on the amount of data returned should not matter because quick responses are required.

For example, let's say that you have an application that processes 50% of all requests made in the application in less than 100 ms. That means that on average, the time it takes to process incoming requests would be less than 100 milliseconds and it would not take more than 100 ms at any moment during a day or week for 50% of incoming requests. If your system is able to work like this consistently, then you have a good idea of what traffic it can handle.

However, if you notice that your system is no longer performing as well as it was in the past, this might be a sign of a potential issue. Make sure you have properly load tested your API to make sure that it will still be able to perform tasks that can't be completed in less than 100 milliseconds. It's better to find these issues before they become a problem so you can get them resolved and avoid any serious consequences.

Testing your API under heavy traffic can help you identify when it will fail.

The following are a few methods to do this:

  • Timing-based testing – If your API is sending an email, then give it enough time to process and send the email then measure how long it takes for the mail to be received. This can also be done with other online transactions such as adding items to a shopping cart or logging into an account.
  • Request-based testing – This tests the resilience of your API by simulating abusive requests that try to break the system. Try sending 100 requests for every one request made by normal users of the API. Monitor how much memory and CPU usage is used during testing and if there are any

Types of Load Testing


A common type of load testing is stress testing, which tests how the application holds up under heavy use. It is usually designed to find out if there are any flaws in the design or implementation of the application by forcing it to perform tasks it would normally not have to do. A lot of times, stress testing involves running a program that keeps on generating errors in order to cause the software to operate outside of its normal range. This type of testing can be helpful for detecting vulnerabilities such as buffer overflows and input validation vulnerabilities.


A spike test is designed to identify when your system can't handle requests coming in all at once. This kind of test will start slowly with low traffic to see how the system reacts then gradually build up until there is a high spike in incoming requests. This can help identify memory leaks and performance issues that are caused by external or internal events such as a hardware failure, system slowdown or even when the API is used at maximum capacity.


A load test simulates real users performing real tasks to see how your API responds under actual conditions of use. It can help identify issues with scalability, load balancing and capacity planning. This type of testing can show how your API will respond to standard user behaviour as well as unusual or abnormal use cases.


A soak test is a classic way of doing the majority of load testing for applications that are able to handle high traffic over time. In other words, it puts your API through its paces to see how it holds up under continuous stress over a period of time. This is done by running the test for an extended period of time with higher loads than what would normally be expected so that any problems can be identified under actual use conditions.


Load testing your APIs is a crucial step in the development process. It can help make sure that you are ready for any type of traffic, and even if there might be an issue with your system. Load testing involves simulating heavy traffic to see how well the API performs and to identify potential flaws in the design or implementation of the application. We have covered different ways to do this including 4 types of tests, like stress, spike, load, and soak tests.

Load Testing Your API's - How to make sure you are Ready?! - [Part 2]

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