10 Free Tools to Load/Stress Test Your Web Applications

Wikipedia defines Load and Stress Testing as “Load testing is the process of putting demand on a system or device and measuring its response. Stress testing refers to tests that determine the robustness of software by testing beyond the limits of normal operation”.

Due to budget constraints, my clients usually ask for some free tools to load/stress test their application, before going live. Here are some free tools to Load/Stress Test web applications. Please note that this is just a listing and is in ‘no particular order’.

The Grinder - The Grinder is a load testing framework that makes it easy to run a distributed test using many load injector machines. Test scripts are written in Jython, and HTTP scripts can be recorded easily from a browser session.

Pylot - Pylot is a free open source tool for testing performance and scalability of web services. It runs HTTP load tests, which are useful for capacity planning, benchmarking, analysis, and system tuning.

Web Capacity Analysis Tool (WCAT) - Web Capacity Analysis Tool (WCAT) is a lightweight HTTP load generation tool primarily designed to measure the performance of a web server within a controlled environment. WCAT can simulate thousands of concurrent users making requests to a single web site or multiple web sites. The WCAT engine uses a simple script to define the set of HTTP requests to be played back to the web server. Extensibility is provided through plug-in DLLs and a standard, simple API.

fwptt - fwptt it's a Web application tester program for load testing web applications. It can record normal and ajax requests. I tested it on asp.net applications, but it should work with jsp, php or other.

JCrawler - JCrawler is an open-source (under the CPL) Stress-Testing Tool for web-applications. It comes with the crawling/exploratory feature. You can give JCrawler a set of starting URLs and it will begin crawling from that point onwards, going through any URLs it can find on its way and generating load on the web application

Apache JMeter – JMeter is open source software, a 100% pure Java desktop application designed to load test functional behavior and measure performance. It was originally designed for testing Web Applications but has since expanded to other test functions.

Siege - Siege is an http load testing and benchmarking utility. It was designed to let web developers measure their code under duress, to see how it will stand up to load on the internet. Siege supports basic authentication, cookies, HTTP and HTTPS protocols. It lets its user hit a web server with a configurable number of simulated web browsers.

http_load - http_load runs multiple http fetches in parallel, to test the throughput of a web server. However unlike most such test clients, it runs in a single process, so it doesn't bog down the client machine. It can be configured to do https fetches as well

Web Polygraph - Web Polygraph is a freely available performance testing tool for caching proxies, origin server accelerators, L4/7 switches, content filters, and other Web intermediaries

OpenSTA - OpenSTA is a distributed software testing architecture designed around CORBA. The current toolset has the capability of performing scripted HTTP and HTTPS heavy load tests with performance measurements from Win32 platforms. However, the architectural design means it could be capable of much more.

I hope you liked this list.


  1. What about the classic torture.pl.

  2. I do prefer http://www.badboy.com.au/ since 2003, I realy do.

    Webtesting for the masses - so under the radar..

  3. PushToTest.com has a free community version of their open source testing framework TestMaker. You can re-use your existing Java, Ruby, Groovy, Python, .Net scripts or Selenium and soapUI recordings. Worth a mention.


  4. The last news from open STA date from 2003, does anyone know if it is still stable or worth using ?

  5. Also take a look at loadUI.

    It's free open source and looks really promising.

    Made by the soapui guys

  6. StresStimulus is a Fiddler extension that replays recorded scenario with unlimited virtual users. It supports constant user load or step load pattern. Graphs show when performance starts degrading.

  7. Does any of these tools actually support Silverlight 5.0? I'd appreciate your help on this one!

  8. I think what you mean is you want to test the service that Silverlight is connecting to.

    Remember that Silverlight runs on the client. However there could be a number of calls to the service from that client, or there could be a number of clients connecting to that service. Either ways, it is the WCF/Web service that you want to load test and see how your Silverlight app performs in this test.

    If you are using VS 2008, check this http://msdn.microsoft.com/en-us/library/ms182561(VS.90).aspx


    If you are using VS 2010, search for VSTS 2010 Load Test -

  9. BlazeMeter is a load testing JMeter cloud based on Apache JMeter. It does offer users a 1 week free trial and a lifetime free tier of up to 50 users. www.blazemeter.com

  10. Hello,

    I found one more useful free online load testing tool - www.onlineloadtest.com

    Best Regards

  11. Very good article, even if it's old i use OpenWebLoad http://openwebload.sourceforge.net/ under Windows, easy to use.

  12. This is my first time i visit here. I found so many entertaining stuff in your blog, especially its discussion. From the tons of comments on your articles, I guess I am not the only one having all the enjoyment here! Keep up the good work.

  13. this blog is great!

    @isiah Thanks for mentioning PushtoTest. Did you know that PushtoTest is now Appvance? Check it out!

  14. Perfomance_TesterApril 2, 2013 at 4:00 AM

    I want to test a .net application with an open source tool. I have to test with 9000 vusers... any suggestions ?

  15. you can run load tests for web applications or API Endpoints for free with LoadFocus.com.
    It works even if you have your own JMeter script, just upload it and it runs from different locations

  16. Here is a good list of load testing tools: http://loadtestservice.com/

  17. 2 more nice tools which are Gatling and Tsung are mentioned in Open Source Load Testing Tools: Which One Should You Use? post which also provides some comparison information on tools benchmarking with sample test scenario and reports.

  18. NeoLoad Free Edition allows to test up to 50 vusers and monitor the app servers. I find it useful for Mobile apps testing.

  19. This comment has been removed by the author.

  20. https://loadfocus.com - load tests with up to 600k clients / test from multiple world regions, extensive load test configuration for full coverage on all scenarios.

  21. Hello everybody!!

    I am a beginner in JMeter, I want to know if I can make performance testing with JMeter on vb.net applications ??? if so how can I do ???

    Thank you in advance and good day

  22. Try loadfocus.com the best load testing tool I have found so far, fast and easy to setup.

  23. Can anyone tell me a single page applications load testing tool which supports https and JavaScript. Need to have it for client side app testing