Welcome to the Android Open Source Project!

Android is an open source software stack for a wide range of 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 you need to create custom variants of the Android stack, port devices and accessories to the Android platform, and ensure your devices meet compatibility requirements.

Android 7.1 Updates Available

What's New

Background App Compilation in A/B System Updates

Examples for installing and configuring otapreopt_script have been added to explain how to use this tool for optimizing user apps so they are ready to run after the device reboots during an A/B system update.

February Android Security Bulletin

The February 2017 Android Security Bulletin has been published along with links to associated fixes. In addition, new build numbers have been published for Nexus 6 running Android 7.0 and 7.1.1 and also Pixel, Pixel XL, Pixel C, Nexus 5X, Nexus 6P, Nexus 9, and Nexus Player running Android 7.1.1 to support the February Android security release.

Android 7.1 CDD

The 7.1 version of the Android Compatibility Definition Document (CDD) has been published. See its change log for a summary of updates.

Diagnosing Native Crashes

Native crashes are now described in detail, fully explaining the types of crashes expected and including the clues for finding them in debuggerd output.

CTS and CTS Verifier 7.0, 6.0, and 5.1

Android Compatibility Test Suite (CTS) and CTS Verifier 7.0 R5, 6.0 R14, and 5.1 R15 are available for download. These releases contain test fixes and verify security patches up to the December 2016 Public Security Bulletin.


A dalvik.annotation.MethodParameters annotation has been added to AOSP after Android 7.1 that is optional and can be used to provide parameter metadata such as parameter names and modifiers. See Dalvik Executable format for a complete description.

Getting Started

Explore the Source

Get the complete Android platform and modify and build it to suit your needs. You can also contribute to the AOSP repository to make your changes available to everyone else in the Android ecosystem.

Android framework summary

Port Android to Devices

Get help porting the latest Android platform to create compelling devices for your customers. Includes documentation for HAL interfaces and details on core technologies such as Android runtime (ART) and over-the-air (OTA) updates.

Make Secure

Follow these examples and instructions to harden your Android devices against malicious attacks. Find out how the Android security program works and learn how to implement the latest features.

Get Compatible

Being Android-compatible lets you offer custom features but still give users and developers a consistent and standard experience across all Android-powered devices. Android provides guidance and a test suite to verify your Android compatibility.

Help this Site

Use the Site Feedback button at the bottom of any page to request content improvements or let us know about errors. To contribute your own updates to the site or to view a complete list of site changes, use the AOSP project docs/source.android.com.