Learn how the pieces fit together, from the kernel to the HALs to updatable system components.
Find out how the Android security program works and learn how to implement the latest features.
Offer a consistent experience with other Android-powered devices for users and app developers.
Android is an open source operating system for mobile devices and a corresponding open source project led by Google. This site and the Android Open Source Project (AOSP) repository offer the information and source code needed to create custom variants of the Android OS, port devices and accessories to the Android platform, and ensure devices meet the compatibility requirements that keep the Android ecosystem a healthy and stable environment for millions of users.

As an open source project, Android's goal is to avoid any central point of failure in which one industry player can restrict or control the innovations of any other player. To that end, Android is a full, production-quality operating system for consumer products, complete with customizable source code that can be ported to nearly any device and public documentation that is available to everyone (in English at source.android.com and in Simplified Chinese at source.android.google.cn).

Just as you can contribute code to AOSP, you can also contribute to AOSP documentation—and we want your input! Android's flexibility and ever-changing codebase means this site needs your feedback to keep content fresh, accurate, and relevant to Android implementors. We encourage you to check the changelog for details on recent AOSP updates and to report bugs or offer suggestions using the Site Feedback at the bottom of every page (or by visiting g.co/androidsourceissue).

Every month the Android security bulletin is published along with the Android Automotive bulletin and Pixel update bulletin.

The Android and Pixel Bulletins are published with links to associated fixes and new build numbers to support the monthly security release.

Android Security Bulletin Pixel Update Bulletin Android Auto Bulletin


The build fingerprint is a unique, human-readable string containing manufacturer information issued to each build that is useful in reporting issues and now documented more fully.
The July 2021 Android and Pixel Bulletins have been published along with links to associated fixes and new build numbers to support the July security release.
Android 11 is released! This site includes documentation for implementing the features, improvements, and enhancements in the newest version of Android.