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Load Testing Tutorial Guide for Beginner

What is Load Testing?

Load testing is highly similar to the performance testing that determines the performance of a system under serious real-life load conditions. This testing explains how an application behaves when it is accessed by multiple users simultaneously. Load testing usually identifies the following conditions given below.

  • It verifies the maximum operating capacity of an application.
  • It verifies the current infrastructure whether it is suitable for running an application or not.
  • It verifies the application’s sustainability concerning the peak user load.
  • It determines the number of concurrent users that can be supported by an application and scalability allowing more users to access it.

It is a type of non-function testing that is commonly used for web-based apps, client-server apps both locally and globally. An environment needs to set up before you start with Load Testing.

Load Testing

Why choose Load Testing?

Mostly sites suffer from serious downtime when accessed by multiple users together. E-commerce sites usually spend heavily in advertising campaigns but not in load testing when the site gets the heavy traffic during its peak hours.

Here are a few examples to understand the concept little better.

  • A potential toy seller, was not able to manage heavy traffic generated by its advertising campaign that resulted in the loss of profits and potential clients both.
  • An airline website was not able to manage 10k+ users together during a festive offer.
  • Encyclopedia Britannica announced free access to their online database as a promotional offer, and it was not able to manage traffic even for a few weeks.

For a few sites, load time was delayed as they encounter the heavy traffic. Here are the few facts for your information:

  • Most users experienced a delay of 8 seconds during web page loading.
  • $5 millions were lost in a year because of the bad performance of sites.

Here are the most convincing reasons why should you adopt Load testing for your next project.

  • It makes you more confident in system performance and its reliability.
  • It helps you to identify system bottlenecks under heavy stress scenario before it actually happens in the production environment.
  • Load testing gives excellent performance against heavy traffic loads and accommodates complementary strategies for performance management and monitoring of a production environment.

QA curriculum

Major Goals of the Load Testing

The load testing mainly works on the response time of a web page. Before you start with the load testing, you should check the following:

  • Quantitative Analysis: You should check either the response time is evaluated and compared in advance.
  • Relevancy: You should check either the response time applies to business processes or not.
  • Realistic: You should check either the response time is justifiable or not.
  • Achievable: You should check either it is possible achieving response time or not.
  • Measurable: You should check either you can measure the response time using a tool or stopwatch.

Load Testing Strategy

If you are planning for load testing your API, then you should design a load testing strategy first. To create a load testing strategy, you should first understand the load requirements, scenarios, and use cases for APIs.

Read: What is STLC? Learn Software Testing Life Cycle Phases

For a retail-based API, you should check for the peak season when product is highly in demand. For example, holidays or Cyber Monday may attract more users than weekdays. During peak time, people visit your website and perform a lot of transactions on your API.

You might decide to build baseline support for 500 users per second. You also want to check the capacity of hardware to determine the total number of servers during the peak loads. You also want to check the traffic loads at different times, and the best idea is using Google Analytics here.

Load Testing Profiles

Once requirements are established well, the next step is converting traffic patterns into load profiles that you will configure or build through load testing tools. Let us discuss four common load profiles that are encountered when working with load testing tools. These are: Load Testing Profiles

  • With a baseline profile, you can check the total number of users, standard deviations, and can have 99 percent confident in establishing strong relationships with customers.
  • A stress profile calculates the maximum number of users before the system breaks at a particular point in time.
  • A peak profile gives you an idea of how many users can be accommodated by an API. Accordingly, you can increase the capacity of an application as required.
  • A soak profile is an excellent style of checking memory leaks in your system. To manage this issue, you can design custom graphs or use cases to measure memory leaks at different time intervals.

How to perform Load Testing?

There are several ways to perform Load Testing. Following are a few strategies for your reference.

  • You can perform the load testing manually. It is one of the best approaches for performing load testing. But it does not provide any repeatable results or measurable level of stress on an application. It is an impossible process to coordinate.
  • If an organization believes that load testing is vital for its application, it may build its own load testing tools.
  • Testers have the flexibility of choosing open source tools that are available free of cost online. They are not as wonderful as paid tools, but you can customize them as per your project requirements.
  • The next category is enterprise-class load testing tools with capture or playback facility. They usually support a wider number of protocols and stimulating the unexpected number of users.

Here is the step by step process for making the Load testing easier for you.

  • At the first step, create a dedicated test environment for load testing.
  • Load the test scenarios.
  • Check the possible number of load testing transaction for an application
  • Check the following:
    • Prepare the test data for each transaction.
    • Check the number of users who can access the system at a particular period.
    • Check the speed of connections. A few are connected through leased lines while others may be connected through a dialup connection
    • Check the different number of browsers or operating systems utilized by users.
    • Server configurations like web, apps, or DB servers, etc.
  • Check for the test scenario monitoring and execution. You can choose various collection metrics for this purpose.
  • Analyze the output thoroughly and make recommendations.
  • Fine-tune the system.
  • Plan for re-testing.

QA Quiz

Load Testing Guidelines

  • Once the application becomes functionally stable, you can plan for the Load Testing.
  • Make the unique data available for Load Testing.
  • Decide on the number of users for different scenarios and scripts.
  • You should avoid the creation of detailed logs for conserving the disk I/O space.
  • You should avoid image downloads for the site.
  • Check for the response time of a web page over the elapsed period, and same should be compared with different test runs as well.

Load Testing vs. Stress Testing

Load Testing Stress Testing
Load testing checks for the system bottlenecks under different load conditions and how it will react once the load on a system increases gradually. Stress testing checks for the breaking point where the system will break once the load increases.

 Load Testing vs. Functional Testing

Functional Testing Load Testing
1). The output of functional tests is easy to determine as preconditions are defined carefully. 2).  The output of functional tests varies slightly. 3). The frequency of executing load test cases is very high. 4). The output for functional test cases depends on the test data. 1). The output of load test cases is not predictable. 2). The output of load tests varies drastically. 3). The frequency of executing load test cases is low. 4). The output of load test cases depends on the number of users.

 Popular Load Testing Tools

 Popular Load Testing Tools LoadNinja:

It is revolutionizing the way how we perform load testing. It is a cloud-based testing tool that empowers the team to record tests instantly and playback comprehensively without any complex dynamic correlation. Further, you may run these test cases in real browsers at scale. The team may optimize the test coverage and cut the load testing time by 60 percent or more.


Read: Manual Testing Salary in Top Locations, Industries & Companies

It is an enterprise-grade load testing tool designed for agile and DevOps apps. It can be integrated with your continuous delivery pipeline to support the performance across the software testing life cycle from components to full system-wide load tests.

Load Runner:

It is an HP tool used by testers to test apps under normal to peak loads as required. It creates loads by generating virtual users that emulate the network traffic. It stimulates the real-time usage in a production environment and assures graphical results too.


It is cloud-based tool offers testing techniques on-demand. A user can perform the real browser testing along with 40+ devices to support multiple browsers together. It allows the multi-location testing with the capacity to stimulate user behavior for web apps, web transactions, portal logins, etc. in a real browser.


It is another flexible load testing tool that supports multiple integrations and allows users to run complex test scenarios. It supports different technologies, protocols, enterprise apps, and operating systems when required.

Pros and Cons of Load testing


  • System bottlenecks can be identified before the actual production.
  • System scalability can be improved when required.
  • System downtime risks can be minimized.
  • System failure costs can be reduced.
  • Overall customer satisfaction can be increased.


  • A little programming background is needed to work with load testing tools.
  • Tools are generally expensive that are supporting virtual users.

Load Testing Use Cases and Examples

Here are a few possible Load Testing use cases and examples for your reference:

Read: List of Top 12 Software Performance Testing Tools to Help You The Most!
  • An airline website was not able to manage 10k+ users together during a festive offer. Next time, it used load testing for evaluating the maximum number of users at a particular time during their promotional offer.
  • A government agency used load testing for evaluating the maximum traffic during the filing date of income tax returns.
  • When the concurrent number of requests are running on the server simultaneously, subjecting the server a massive volume of traffic, load testing is again useful here to check the maximum load on a server.
  • When a huge number of files are transferred to and from the hard disk, you have to measure the speed of transfer to accelerate the process, and it can be made possible with the help of load testing.
  • Load testing is required when you are interested in downloading a large number of files from a Company website to test its performance.

Best Practices for Load Testing

  • Business goals identification: a depth understanding of business goals and scope will draw clear guidelines to inform the process.
  • Key measures determination for an application: It includes throughput, response time, resource utilization, maximum user load, and business performance metrics.
  • Decide on the best tool: you need to check the most suitable tools that cater to your requirements. A few we have already discussed for your reference like Load Runner, NeoLoad, WebLoad, LoadView, etc.
  • Test case generation: when you are writing a test case, make sure that all positive and negative scenarios are taken into account. It helps in designing the most powerful and accurate test cases based on project requirements.
  • Understand the environment: If you want to test different types of deployments, then you should create configurations for the same. Also, you should check the different capacities of the system like hardware, software, security, and networks, etc.
  • Run tests incrementally: When all tests are executed or run together, it may result in system failure. So, determine the volume first and run them gradually.
  • Focus on customers more: keep in mind that customer satisfaction is a vital achievement for a business. Satisfied customers usually visit your site again and again when required.

QA Demo Class

Scriptless Load Testing – All you should know

When it comes to APIs, people usually take a straightforward approach and run basic functional tests through a browser. These are acceptable starting points in case of functional testing and don’t scale up on functionality. At the same time, performance focused testing tools require a lot of custom coding when it comes to APIs or endpoints.

Features like JSON path parsing, chaining API requests in a sophisticated scenario, and validating an API schema are not the native capabilities of tools. These script-based platforms are designed to record transactions, not APIs. In this way, a lot of functionalities is lost for APIs when translated to backend APIs.

When you are working with solutions which are open source load testing solutions, you are expected to create an API test backed by a script.  Although there is no scripting experience required and this script creates the load using code just written by you. What are the possible considerations if writing code for the first time?

  • You should check the expertize to debug and run the test case script in a shorter period.
  • You should check how to maintain these scripts and their complexity when they bloat in size.
  • You should check how to reuse functional tests at a certain point of time.

When you are using script-based load testing tools, most of your time goes in creating and maintaining test scripts. As your scripts grow in number, you are left with maintaining scripts all day. It is also true that each program has its own style for writing the same scripts. They add their own functions and procedures to those scripts.

It generally ends up in challenges when a new tester joins the team and evaluating scripts written by programmers. Here, team leader or managers should establish a process as per coding standards to avoid issues. There are requirements of more resources and overhead that gets into solutions and usually script-based.

Here comes the concept of scriptless load testing in trend. You may prefer tools that are not based on the script and makes it easy to create a load test as per API specifications. The best example here is LoadUI for scriptless load testing. If you have already generated functional test cases, they can be converted to load tests in just a few minutes and reuse the existing functional tests as load tests with the help of SoapUI tool.

These two tools SoapUI and LoadUI enables you to perform a lot of activities with APIs; these are:

  • Learn to work with JSON and XML through point and click tools.
  • Learn refactoring APIs with definition usage.
  • Learn method chaining among multiple API test cases.
  • Learn to transfer parameters, properties, from one response to other requests as per the requirement.
  • Learn linking data elements from Excel, CSV, and databases to parameters in JSON and XML.


Load testing is a critical part of the software testing process as it ensures that software performs to render the maximum user satisfaction. When load testing is performed successfully, it results in high-quality software as per the latest industry standards. It is not easy performing load testing, so the best idea is taking help from experts or learn using load testing tools to make the API testing easier and more flexible for you. To know more on Load testing and similar quality concepts, join QA certification program at JanBask Training and learn using different testing tools practically.

Read: Top 100 QA Testing Interview Questions and Answers for year 2022

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