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Contributing to Polymer

There are many ways to contribute to the Polymer project! We welcome and truly appreciate contribution in all forms - issues and pull requests to the main library, issues and pull requests to the elements the Polymer team maintains, issues and pull requests to one of our many Polymer-related tools, and of course we love to hear about any Polymer elements that you build to share with the community!


Communicating with the Polymer team

Beyond Github, we try to have a variety of different lines of communication open:

The Polymer Repositories

Because of the component-based nature of the Polymer project, we tend to have lots of different repositories. Our main repository for the Polymer library itself is at File any issues or pull requests that have to do with the core library on that repository, and we'll take a look ASAP.

We keep all of the element "product lines" that the Polymer team maintains and distributes in the PolymerElements organization. For any element-specific issues or pull requests, file directly on the element's repository, such as the paper-button repository at Of course, the elements built by the Polymer team are just a tiny fraction of all the Polymer-based elements out there - catalogs of other web components include and

The GoogleWebComponents element product line is maintained by teams all across Google, and so is kept in a separate organization: the GoogleWebComponents org. Feel free to file issues and PR's on those elements directly in that organization.

We also track each element product line overall in "meta-repos", named as $PRODUCTLINE-elements. These include paper-elements, iron-elements, gold-elements, and more. Feel free to file issues for element requests on those meta-repos, and the README in each repo tracks a roadmap for the product line.

Contributor License Agreement

You might notice our friendly CLA-bot commenting on a pull request you open if you haven't yet signed our CLA. We use the same CLA for all open-source Google projects, so you only have to sign it once. Once you complete the CLA, all your pull-requests will automatically get the cla: yes tag.

If you've already signed a CLA but are still getting bothered by the awfully insistent CLA bot, it's possible we don't have your GitHub username or you're using a different email address. Check the information on your CLA or see this help article on setting the email on your git commits.

Complete the CLA


Filing bugs

The Polymer team heavily uses (and loves!) Github for all of our software management. We use Github issues to track all bugs and features.

If you find an issue, please do file it on the repository. The Polymer/polymer issues should be used only for issues on the Polymer library itself - bugs somewhere in the core codebase.

For issues with elements the team maintains, please file directly on the element's repository. If you're not sure if a bug stems from the element or the library, air toward filing it on the element and we'll move the issue if necessary.

We love examples for addressing issues - issues with a Plunkr, jsFiddle, or jsBin will be much easier for us to work on quickly. You can start with this jsbin which sets up the basics to demonstrate a Polymer element.

Occasionally we'll close issues if they appear stale or are too vague - please don't take this personally! Please feel free to re-open issues we've closed if there's something we've missed and they still need to be addressed.

Contributing Pull Requests

PR's are even better than issues. We gladly accept community pull requests. In general across the core library and all of the elements, there are a few necessary steps before we can accept a pull request:

  • Open an issue describing the problem that you are looking to solve in your PR (if one is not already open), and your approach to solving it. This makes it easier to have a conversation around the best general approach for solving your problem, outside of the code itself.
  • Sign the CLA, as described above.
  • Fork the repo you're making the fix on to your own Github account.
  • Code!
  • Ideally, squash your commits into a single commit with a clear message of what the PR does. If it absolutely makes sense to keep multiple commits, that's OK - or perhaps consider making two separate PR's.
  • Include tests that test the range of behavior that changes with your PR. If you PR fixes a bug, make sure your tests capture that bug. If your PR adds new behavior, make sure that behavior is fully tested. Every PR must include associated tests. (See Unit tests for more.)
  • Submit your PR, making sure it references the issue you created.
  • If your PR fixes a bug, make sure the issue includes clear steps to reproduce the bug so we can test your fix.

If you've completed all of these steps the core team will do its best to respond to the PR as soon as possible.

Contributing Code to Elements

Though the aim of the Polymer library is to allow lots of flexibility and not get in your way, we work to standardize our elements to make them as toolable and easy to maintain as possible.

All elements should follow the Polymer element style guide, which defines how to specify properties, documentation, and more. It's a great guide to follow when building your own elements as well, for maximum standardization and toolability. For instance, structuring elements following the style guide will ensure that they work with the iron-component-page element, an incredibly easy way to turn any raw element directly into a documentation page.

Contributing Code to the Polymer library

We follow the most common javascript and HTML style guidelines for how we structure our code - in general, look at the code and you'll know how to contribute! If you'd like a bit more structure, the Google Javascript Styleguide is a good place to start.

Polymer also participates in Google's Patch Rewards Program, where you can earn cold, hard cash for qualifying security patches to the Polymer library. Visit the patch rewards page to find out more.

Unit tests

All Polymer projects use web-component-tester for unit tests. The polyserve utility is helpful for running tests in the browser.

For maximum flexibility, install web-component-tester and polyserve locally:

npm install -g polyserve web-component-tester

Running the Polymer library unit tests

To run the Polymer library unit tests:

  1. Clone the Polymer repo.

  2. Install the dependencies:

    npm install && bower install
  3. Run the tests:

    npm test

    Or if you have web-component-tester installed locally:


To run individual test suites:

npm test path/to/suite


wct path/to/suite

For example:

npm test test/unit/template.html

You can also run tests in the browser:


Navigate to:


Running Polymer element unit tests

To run the element unit tests, you need a global install of web-component-tester or polyserve (or both).

  1. Clone the element repo.

  2. Install the dependencies.

    bower install
  3. Run the tests:


    Or run the tests in a browser:


    Navigate to:


Configuring web-component-tester

By default, web-component-tester runs tests on all installed browsers. You can configure it to run tests on a subset of available browsers, or to run tests remotely using Sauce Labs.

See the web-component-tester README for information on configuring the tool.