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25 free tools to measure website performance

Recent findings indicate 47 percent of consumers expect an e-commerce page to load in two seconds or less.  Site performance is a key factor in a consumer’s loyalty.  What about sites other than retail such as blogs, directories, news and etc.?  A user waits 5 seconds on average for a page to load before taking their business elsewhere.

We’ve compiled list of freely available tools you can use to measure performance of your website.  But before you go through the list, here is an excellent video by Google on the topic of open source tools used for performance testing.  The video provides some good details about what to look for during load tests and how to avoid performance issues in the first place.

Google Page Speed

Page Speed is an open-source Firefox/Firebug Add-on. Webmasters and web developers can use Page Speed to evaluate the performance of their web pages and to get suggestions on how to improve them.

Page Speed performs several tests on a site’s web server configuration and front-end code. These tests are based on a set of best practices known to enhance web page performance. Webmasters who run Page Speed on their pages get a set of scores for each page, as well as helpful suggestions on how to improve its performance.

Yahoo! YSlow

YSlow analyzes web pages and tells you why they’re slow based on the best practices for high performance web sites. YSlow is a Firefox add-on integrated with the popular Firebug web development tool. This tool has helped improve the performance on over 50 Yahoo! properties by 25-50%.  Here is a nice video introduction and usage of YSlow.

Introducing YSlow @ Yahoo!7 Video


Httperf is a tool for measuring web server performance. It provides a flexible facility for generating various HTTP workloads and for measuring server performance. The focus of httperf is not on implementing one particular benchmark but on providing a robust, high-performance tool that facilitates the construction of both micro- and macro-level benchmarks.

It does so much more for it’s simplicity.  It can simulate multiple sessions and transactions including replaying ‘live’ traffic from your web access log.   Check out this introductory document below on how it can help measure performance.

httperf – A Tool for Measuring Web Server Performance –

Pagetest (IE only)

The facts remain, IE is still very popular and widely used.  This tool is only available on IE browsers but nevertheless it is very powerful.  Pagetest is an open source tool for measuring and analyzing web page performance right from your web browser.  AOL developed Pagetest internally to automate load time measurement of its many websites, and it has evolved into a powerful tool for web developers and software engineers in testing their web pages and getting instant feedback.  Check out this great video on how to analyze and optimize your website for performance.

Optimizing Web Performance with AOL Pagetest from Dave Artz on Vimeo.

  • You can also use an online version of Pagetest here.

Apache JMeter

Apache 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. Here is a quick video tutorial on using Jmeter.

It may be used to test performance both on static and dynamic resources (files, Servlets, Perl scripts, Java Objects, Data Bases and Queries, FTP Servers and more). It can be used to simulate a heavy load on a server, network or object to test its strength or to analyze overall performance under different load types. You can use it to make a graphical analysis of performance or to test your server/script/object behavior under heavy concurrent load.


Selenium IDE is an integrated development environment for Selenium tests. It is implemented as a Firefox extension, and allows you to record, edit, and debug tests. Selenium IDE includes the entire Selenium Core, allowing you to easily and quickly record and play back tests in the actual environment that they will run.

Selenium IDE is not only recording tool: it is a complete IDE. You can choose to use its recording capability, or you may edit your scripts by hand. With autocomplete support and the ability to move commands around quickly, Selenium IDE is the ideal environment for creating Selenium tests no matter what style of tests you prefer.


WebInject is a free tool for automated testing of web applications and web services. It can be used to test individual system components that have HTTP interfaces (JSP, ASP, CGI, PHP, AJAX, Servlets, HTML Forms, XML/SOAP Web Services, REST, etc), and can be used as a test harness to create a suite of [HTTP level] automated functional, acceptance, and regression tests. A test harness allows you to run many test cases and collect/report your results. WebInject offers real-time results display and may also be used for monitoring system response times.

WebInject can be used as a complete test framework that is controlled by the WebInject User Interface (GUI). Optionally, it can be used as a standalone test runner (text/console application) which can be integrated and called from other test frameworks or applications.


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.  Here is a pretty good article on how to use Siege.

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.  Sample usage:

% ./http_load -rate 5 -seconds 10 urls
49 fetches, 2 max parallel, 289884 bytes, in 10.0148 seconds
5916 mean bytes/connection
4.89274 fetches/sec, 28945.5 bytes/sec
msecs/connect: 28.8932 mean, 44.243 max, 24.488 min
msecs/first-response: 63.5362 mean, 81.624 max, 57.803 min
HTTP response codes:
code 200 -- 49

HTTP Test Tool

HTTP Test Tool is a script based tool for testing and benchmarking web applications, web servers, proxy servers and web browsers.  httest can emulate clients and servers even in the same test script. Emulating servers is a unique feature, very usefull for testing proxy servers, web browsers and HTTP clients.


ApacheBench is a command line computer program for measuring the performance of HTTP web servers. It was designed to give an idea of the performance that a given Apache installation can provide. In particular, it shows how many requests per second the server is capable of serving.  The ab tool comes bundled with your standard Apache, you can find it in apache install bin directory.


OpenSTA is a distributed software testing architecture designed around CORBA, it was originally developed to be commercial software by CYRANO. 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

OpenSTA is a distributed software testing architecture designed around CORBA, it was originally developed to be commercial software by CYRANO. 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.


OpenWebLoad is a tool for load testing web applications. It aims to be easy to use and providing near real-time performance measurements of the application under test. This is particulary useful when you are doing optimization as you can see the impact of your changes almost immediately.


Open source tool by Corey Goldberg for generating concurrent http loads. Define test cases in an XML file – specify requests – url, method, body/payload, etc – and verifications. Verification is by matching content to regular expressions and with HTTP status codes. HTTP and HTTPS (SSL) support. Monitor and execute test suites from GUI (wxPython), and adjust load, number of agents, request intervals, rampup time, test duration. Real-time stats and error reporting are displayed.


An open-source stress-testing tool for web apps; includes crawling/exploratory features. User 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. Load parameters (hits/sec) are configurable via central XML file; fires up as many threads as needed to keep load constant; includes self-testing unit tests. Handles http redirects and cookies; platform independent.


Open-source tool written in ‘C’, simulating application load and behavior of tens of thousand HTTP/HTTPS and FTP/FTPS clients, each with its own source IP-address. In contrast to other tools curl-loader is using real C-written client protocol stacks, namely, HTTP and FTP stacks of libcurl and TLS/SSL of openssl. Activities of each virtual client are logged and collected statistics include information about: resolving, connection establishment, sending of requests, receiving responses, headers and data received/sent, errors from network, TLS/SSL and application (HTTP, FTP) level events and errors.


FunkLoad is a functional and load web tester, written in Python, whose main use cases includes Functional testing of web projects and regression testing as well. It?s also capable of performance testing your app by loading the web application and monitoring your servers which helps to pinpoint bottlenecks, giving a detailed report of performance measurement. FunkLoad also expose bugs that do not surface in cursory testing, like volume testing or longevity testing.


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.

Hammerhead – Web Testing Tool

Hammerhead is a web site coverage, HTTP load generator, HTTP benchmarking, and stress testing tool. It has been designed to emulate multiple users from multiple IP addresses at maximum speed.

Raw Load Tester

The application calls the URL you select as many times as you choose and tells you how long it took the server to respond. It writes some additional runtime details to the PHP log file so you can optionally do more granular analysis afterwards. Although the server processes most of the statistics, all URL requests come from the browser. You can run as many browsers and workstations simultaneously as you want.

Apache Flood

Flood is a profile-driven HTTP load tester. In layman’s terms, it means that flood is capable of generating large amounts of web traffic. Flood’s flexibility and power arises in its configuration syntax. It is able to work well with dynamic content.


LoadSim is a web application load simulator. It allows you to create simulations and have those simulations run against your webserver.


Open source Java program for accessing web sites without a browser.  Ideally suited for automated unit testing of web sites when combined with a Java unit test framework such as JUnit. Emulates the relevant portions of browser behavior, including form submission, basic http authentication, cookies and automatic page redirection, and allows Java test code to examine returned pages as text, an XML DOM, or containers of forms, tables, and links. Includes ServletUnit to test servlets without a servlet container.


IeUnit is a simple framework to test logical behaviors of web pages. It helps software engineers to create, organize and execute functional unit tests.


Imprimatur is designed to be the simplest web application functional testing tool that could possibly work. It sends HTTP requests to the application, and then validates the responses using regular expressions. The tests are written in an XML file. Imprimatur supports most of HTTP including: GET, POST, PUT, HEAD and DELETE methods, HTTP authentication, setting and checking of HTTP headers, and file uploads.

  1. BooQa
    October 30th, 2009 at 01:23 | #1

    Great list! I like httperf and other simpler tools…apache flood seems interesting too!

  2. Ghopa
    November 3rd, 2009 at 20:34 | #2

    This is wonderful.

  3. Keyur
    July 19th, 2011 at 00:07 | #3

    Excellent list. I personally use google page speed and yslow. Also aol page test is great.

    You could add fiddler and httpwatch to your list.

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  1. April 2nd, 2010 at 07:03 | #1