Screenster!

Selenium is a suite of tools specifically for testing web applications. Selenium IDE is a Firefox add-on that records clicks, typing, and other actions to make a test, which you can play back in the browser. Selenium Remote Control (RC) runs your tests in multiple browsers and platforms. Tweak your tests in your preferred language.

Kantu allows you to visually automate your task, and makes web automation fun again. It lets you create solutions for web automation, web scraping or web testing in minutes. It's like the ultimate robot stand-in for all of your web browser automation needs! Whatever you used to do manually, Kantu can do automatically -- stuff like filling out forms, clicking on links, performing inquiries, you name it, Kantu has it. Multiple page forms? Not a problem for Kantu.

PhantomJS is a headless WebKit with JavaScript API. It has fast and native support for various web standards: DOM handling, CSS selector, JSON, Canvas, and SVG.

CasperJS is an open source navigation scripting & testing utility written in Javascript for the PhantomJS WebKit headless browser and SlimerJS (Gecko). It eases the process of defining a full navigation scenario and provides useful high-level functions, methods & syntactic sugar for doing common tasks such as:* defining & ordering browsing navigation steps* filling & submitting forms* clicking & following links* capturing screenshots of a page (or part of it)* testing remote DOM* logging events* downloading resources, including binary ones* writing functional test suites, saving results as JUnit XML* scraping Web contents »

SlimerJS is a scriptable browser. It allows you to manipulate a web page with a Javascript script: opening a webpage, clicking on links, modifying the content... It is useful to do functional tests, page automaton, network monitoring, screen capture etc.

iMacros was designed to automate the most repetitious tasks on the web. If there’s an activity you have to do repeatedly, just record it in iMacros. The next time you need to do it, the entire macro will run at the click of a button! With iMacros, you can quickly and easily fill out web forms, remember passwords, create a webmail notifier, download information from other sites, scrape the Web (get data from multiple sites), and more. You can keep the macros on your computer for your own use, or share them with others by embedding them on your homepage, blog, company Intranet or any social bookmarking service. The uses are limited only by your imagination! »

The httest provides a large variety of HTTP-related functionality, useful for implementing all kinds of HTTP-based tests.

Pincers - Web automation DSL on top of webdriver (and nokogiri)

The lack of integration among open-source test automation frameworks amid unaffordable commercial solutions is a major challenge for effectively applying test automation.

Watir, pronounced water (acronym standing for "Web Application Testing in Ruby"), is an open-source (BSD) family of Ruby libraries for automating web browsers. It allows you to write tests that are easy to read and maintain. It is simple and flexible.

WatiN - Web Application Testing In .Net

Robot Framework is a generic test automation framework for acceptance testing and acceptance test-driven development (ATDD). It has easy-to-use tabular test data syntax and it utilizes the keyword-driven testing approach. Its testing capabilities can be extended by test libraries implemented either with Python or Java, and users can create new higher-level keywords from existing ones using the same syntax that is used for creating test cases.

Squash TA is a toolbox for functional testing automation and is dedicated to the industrialization of automated tests execution. Squash TA natively interacts with various open source robots like Selenium. Squash TA is a management controller of automated tests of Web applications, webservices and batches.