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Performance Guidelines

Use Lighthouse to test and improve a site's performance. There is a hard requirement of reaching a score of 100 for Accessibility and 90 for Performance on both mobile and desktop.

For App Engine Projects

Please review our Optimizing Performance resource for App Engine applications.

Maintainability Guidelines

  • HTML should only cover document structure, move all styling into style sheets, and all behavior into scripts.
  • Limit the number of style sheets and scripts.
  • Avoid presentational ID and class names: use functional or generic names instead.
  • Comment complex code.
  • Include a README file explaining any necessary build tools or processes.

Third Party Libraries

For Sensitive Domain Projects

Please discuss any use of third party libraries on a sensitive domain with the ATL team. It is incredibly rare that a third party library will be approved and made available for use on such domains. Of course we love it if you want to use any of the tools hosted on the Google Libraries API.

For Non-Sensitive Domain Projects

Non-sensitive domain projects are a little less strict in that they only require licensing approval. If you have third party scripts/tools/libraries that you are considering, please include them in your technical design document and alert the ATL or PMM on your project. Once they are approved you will need to host the scripts from your application. Linking to a 3rd party source for the script is strictly forbidden. Of course we love it if you want to use any of the tools hosted on the Google Libraries API.

Open Source Software

Any use of Open Source software must be reviewed by Google before it can be used. This is done on a case-by-case basis: being granted permission to use software in one project does not guarantee that it will be granted in the next. You will need approval for each use.

Brand Identity Guidelines