A browser automation framework and ecosystem
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Selenium is an umbrella project encapsulating a variety of tools and libraries enabling web browser automation. Selenium specifically provides infrastructure for the W3C WebDriver specification — a platform and language-neutral coding interface compatible with all major web browsers.

The project is made possible by volunteer contributors who've generously donated thousands of hours in code development and upkeep.

Selenium's source code is made available under the Apache 2.0 license.


Narrative documentation:

API documentation:

Pull Requests

Please read CONTRIBUTING.md before submitting your pull requests.


Selenium uses a custom build system aptly named crazyfun available on all fine platforms (Linux, Mac, Windows). We are in the process of replacing crazyfun with buck, so don't be alarmed if you see directories carrying multiple build directive files. For reference, crazyfun's build files are named build.desc, while buck's are named simply BUCK.

To build Selenium, in the same directory as this file:


The order of building modules is determined by the build system. If you want to build an individual module (assuming all dependent modules have previously been built), try the following:

./go //javascript/atoms:test:run

In this case, javascript/atoms is the module directory, test is a target in that directory's build.desc file, and run is the action to run on that target.

As you see build targets scroll past in the log, you may want to run them individually. crazyfun can run them individually, by target name as long as :run is appended (see above).

To list all available targets, you can append the -T flag:

./go -T


Although the plan is to return to a vanilla build of Buck as soon as possible, we currently use a fork hosted at https://github.com/shs96c/buck To build using Buck, first clone that repo and build using ant. Then add Buck's "bin" directory to your PATH.

To obtain a list of all available targets:

buck targets

And build a particular file:

buck build //java/client/src/org/openqa/selenium:webdriver-api

There are aliases for commonly invoked targets in the .buckconfig file, and these aliases can be invoked directly:

buck build htmlunit

All buck output is stored under "buck-out", with the outputs of build rules in buck-out/gen.

If you are doing a number of incremental builds, then you may want to use buckd, which starts a long-lived buck process to watch outputs and input files. If you do this, consider using watchman too, since the Java 7 file watcher isn't terribly efficient. This can be cloned from https://github.com/facebook/watchman


Although the build system is based on rake it's strongly advised to rely on the version of JRuby in third_party/ that is invoked by go. The only developer type who would want to deviate from this is the “build maintainer” who's experimenting with a JRuby upgrade.

Note that all Selenium Java artefacts are built with Java 7 (mandatory). Those will work with any Java >= 7.

Optional Requirements

  • Python 2.6.x to 2.7 (without this, Python tests will be skipped)
  • Ruby 1.9.3

Internet Explorer Driver

If you plan to compile the IE driver you also need:

The build will work on any platform, but the tests for IE will be skipped silently, if you are not building on Windows.

Common Tasks

For an express build of the binaries we release run the following from the directory containing the Rakefile:

./go clean release

All build output is placed under the build directory. The output can be found under build/dist. If an error occurs while running this task complaining about a missing Albacore gem, the chances are you're using rvm. If this is the case, switch to the system ruby:

rvm system

Of course, building the entire project can take too long. If you just want to build a single driver, then you can run one of these targets:

./go chrome
./go firefox
./go htmlunit
./go ie

As the build progresses, you'll see it report where the build outputs are being placed. Of course, just building isn't enough. We should really be able to run the tests too. Try:

./go test_chrome
./go test_firefox
./go test_htmlunit
./go test_ie

Note that the test_chrome target requires that you have the separate Chrome Driver binary available on your PATH.

If you are interested in a single language binding, try one of:

./go test_java
./go test_dotnet
./go test_rb
./go test_javascript

To run all the tests just run:

./go test

This will detect your OS and run all the tests that are known to be stable for every browser that's appropriate to use for all language bindings. This can take a healthy amount of time to run.

To run the minimal logical Selenium build:

./go test_javascript test_java

As a side note, none of the developers run tests using Cygwin. It is very unlikely that the build will work as expected if you try and use it.


The code base is generally segmented around the languages used to write the component. Selenium makes extensive use of JavaScript, so let's start there. Working on the JavaScript is easy. First of all, start the development server:

./go debug-server

Now navigate to http://localhost:2310/javascript. You'll find the contents of the javascript/ directory being shown. We use the Closure Library for developing much of the javascript, so now navigate to http://localhost:2310/javascript/atoms/test.

The tests in this directory are normal HTML files with names ending with _test.html. Click on one to load the page and run the test. You can run all the javascript tests using:

./go test_javascript

Maven POM files

Ignore the Maven POM file present in the same directory. It is only used for releasing to jars to Maven Repository (public or local), and is not considered the main build mechanism.

Here is the public Selenium Maven repository.

Build Output

./go only makes a top-level build directory. Outputs are placed under that relative to the target name. Which is probably best described with an example. For the target:

./go //java/client/src/org/openqa/selenium:selenium-api

The output is found under:


If you watch the build, each step should print where its output is going. Java test outputs appear in one of two places: either under build/test_logs for JUnit or in build/build_log.xml for TestNG tests. If you'd like the build to be chattier, just append log=true to the build command line.

Help with go

More general, but basic, help for go

./go --help

Remember, go is just a wrapper around Rake, so you can use the standard commands such as rake -T to get more information about available targets.

Maven per se

If it is not clear already, Selenium is not built with Maven, it is built with Crazy-Fun though that is invoked with go as outlined above so you do not really have to learn too much about that.

That said, it is possible to relatively quickly build selenium pieces for Maven to use. You are only really going to want to do this when you are testing the cutting-edge of Selenium development (which we welcome) against your application. Here is the quickest way to build and deploy into you local maven repository (~/.m2/repository), while skipping Selenium's own tests.

./go release
cd maven
mvn clean install

This sequence will push some seven or so jars into your local Maven repository with something like 'selenium-server-2.0-SNAPSHOT.jar' as the name.

Useful Resources

Refer to the Building Web Driver wiki page for the last word on building the bits and pieces of Selenium.