The Performance Testing Tools for Web Applications book is a guide to many Open Source performance testing tools available today. The test tools reviewed are good for load testing web applications, benchmarking your network equipment, giving you an insight into how to speed up your application or website.
This guide offers a review of different open source performance testing software packages. Some of these tools may be used to check performance on websites, some for applications or some for both. One thing all the tools share is that they are free. The package are Apache JMeter, Gatling, Superpoke, Load Tester by NAG, Loader.io, Nagios Packet Builder, WBSping, WebLOAD and JMETER – JMeter GUI. The book provides an overview of each tool’s architecture and technology used, compares them to one another on various criteria that include release date, license type, programming
JMeter 
JMeter is the most popular open-source tool in the performance space to help measure load time.
Apache JMeter describes itself as a Java application that was designed specifically for load testing with the ability to measure application performance and response times.
JMeter was built to pretty much be the open-source alternative to LoadRunner, so you’ll find it has lots of sophisticated features. It’s a thick client Java app that’s largely driven by right clicks. It’s a little weird, but it’s got a lot of power. Also, all the features a professional load tester wants are available on JMeter.
Some features are:
- The ability to performance test a host of technologies using a range of protocols such as Java Objects, Web HTTP/HTTPS, SOAP and Rest Services, FTP, Databases with JDBC
- A nice IDE you can use for recording, building, and debugging your performance tests
- Starting with JMeter 3.1 Groovy is the default programming language
- One of the more popular performance testing tools
- Can configure it to help test mobile performance of mobile apps
It currently has 5.1k stars on GitHub.
Although JMeter is one of the more popular test tools, it does have some shortcomings.
For instance, JMeter can be a bit difficult to scale for a large distributed test; especially if you have to set up a bunch of machines since you have to configure them to talk to each other. There is also a host of orchestrating problems in executing large JMeter tests.
That’s where a tool open sourced by BlazeMeter—Taurus—can help you out.
Taurus 
While not technically a load testing tool Taurus acts more like a wrapper on top of other solutions that hides the complexity of running performance tests.
The power of Taurus is that it allows you to write your tests in YAML.
You can actually describe a full-blown script in about ten lines of text, which gives teams the ability to describe their tests in a YAML or JSON file. The YAML is a human, readable, edible approach that enables you to describe a test in a simple text file.
This is a big leap forward from the old days of having to bring up a big, heavy vendor-specific record and scripting tool for load time measuring.
Features
- This should also allow more members of your team to contribute to performance tests. Also, since your test cases are written in YAML the tests are much more readable, making them easier to perform code reviews on.
- Taurus basically fits performance testing into your CI/CD pipeline much more efficiently.
- Taurus provides a sort of abstraction layer on top of JMeter, as well as some other tools like Locust, Gatling, the Grinder and Selenium.
It currently has 1.4k stars on GitHub.
Locust 
Locust is a simple-to-use, distributed, user load testing tool that can help you capture response times.
What scripting languages does it use? The best one — Python! 🙂
It is used to helps performance test websites or other applications.
Locust can also help you figure out how many concurrent users a system can handle.
Where tools like jMeter are based upon, a thread-based architecture that consumes a lot of resources. Locust uses an event-based approach that uses fewer resources.
Rahul Solanki a technical leader at BlueConch Technologies mentioned to me that when he compared it with JMeter, the number of resources that Locust occupies was around 70 percent less.
If you’re familiar with the term “load generators,” Locust uses the term “swarm”–as in you can point a swarm of locusts to put a load on your website.
You can define the behavior you want for each of your Locust instances. It also gives you the ability to monitor the swarming process from a web UI in real-time.
Some of the cool key features you get with Locust are:
- The ability to create your test scenarios using straight Python
- You can easily scale the number of users you need to emulate
- It has a nice Web-based UI
- Extensible
- Good for testing APIs
Cons
Since its a newer tool it has far fewer plugins than JMeter
It currently has 15.7k stars on GitHub.
WebLOAD
Enterprise-grade load and performance testing tool for web applications. WebLOAD is a tool of choice for enterprises with heavy user load and complex testing requirements. It allows you to perform load and stress testing on any internet application by generating load from the cloud and on-premises machines.
WebLOAD’s strengths are its flexibility and ease of use – enabling you to quickly define the tests you need with features like DOM-based recording/playback, automatic correlation, and JavaScript scripting language.
The tool provides a clear analysis of your web application performance, pinpointing issues and bottlenecks that may stand in the way of achieving your load and response requirements.
WebLOAD supports hundreds of technologies – from web protocols to enterprise applications and has built-in integration with Jenkins, Selenium and many other tools to enable continuous load testing for DevOps.
System Requirements: Windows, Linux
LoadNinja
LoadNinja by SmartBear allows you to quickly create scriptless sophisticated load tests, reduces testing time by 50%, replaces load emulators with real browsers, and get actionable, browser-based metrics, all at ninja speed.
You can easily capture client-side interactions, debug in real-time, and identify performance problems immediately. LoadNinja empowers teams to increase their test coverage without sacrificing quality by removing the tedious efforts of dynamic correlation, script translation, and script scrubbing.
With LoadNinja, engineers, testers and product teams can focus more on building apps that scale and focus less on building load testing scripts.
Features:
- Scriptless load test creation & playback with InstaPlay recorder.
- Real browser load test execution at scale.
- VU Debugger – debug tests in real-time.
- VU Inspector – manage virtual user activity in real-time.
- Hosted on the cloud, no server machine & upkeep required.
- Sophisticated browser-based metrics with analytics and reporting features.
ReadyAPI Performance
SmartBear offers an all-in-one automated API Testing Platform called ReadyAPI. It contains various tools like Swagger & SwaggerHub, SoapUI NG, ReadyAPI Performance, Secure Pro, ServiceV, and AlertSite.
ReadyAPI Performance is an API tool for load testing. This API testing tool will assure you that your APIs can perform anywhere. It will let you install load agents on any server or cloud as well as on-premise. It provides advanced performance metrics for load test runs.
SoapUI NG is a tool for functional testing and you can use these functional testing use cases designed in the SOAPUI for performance testing.
This load testing tool will help you with testing the speed, scalability, and performance of the APIs, Servers, and Network Resources. It has features of flexible load generation, parallel API load tests, server monitoring, and pre-built load templates.
Kobiton
Kobiton offers flexible real device access options that include a public cloud, private cloud, and on-premises. With Kobiton’s Performance Testing capabilities, users can integrate real device testing with Load and Stress testing solutions. This can be done manually, with automation via script-based solutions like Appium, and using Kobiton’s AI-driven scriptless engine. With Kobiton, you have a platform solution that allows for insight into app and device-specific performance metrics that easily integrates with solutions like NeoLoad or JMeter.
Features:
- Kobiton’s device lab management will let you connect with devices in the cloud, your local on-premises devices as well as on-desk devices.
- Create automated test scripts from manual tests and are executable on multiple devices simultaneously.
- Users can test crucial app and website-specific performance with Kobiton’s Payload capture
- Automatic test case generation from the manual session
Conclusion
Web applications are the future of software, but building them is complex. As businesses look to move their applications to cloud computing, it’s essential that they be able to trust the companies that host their applications, and that these hosting companies be able to demonstrate that they can keep these applications up and running at all times. To protect their web apps in the cloud, businesses need tools to make sure they can scale reliably. Fortunately, there are a number of free performance testing tools available for developing scalable web apps in the cloud.