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Corona Warn App - Android


The goal of this project is to develop the official Corona-Warn-App for Germany based on the exposure notification API from Apple and Google. The apps (for both iOS and Android) use Bluetooth technology to exchange anonymous encrypted data with other mobile phones (on which the app is also installed) in the vicinity of an app user's phone. The data is stored locally on each user's device, preventing authorities or other parties from accessing or controlling the data. This repository contains the native Android implementation of the Corona-Warn-App. Visit our FAQ page for more information and common issues

Known Issues

  • Activating exposure logging on a test version of the Android app requires a Google account which has been allowlisted for this purpose by Google (see Exposure Notifications implementation guide - Prerequisites). Google only allowlists official development partners: general CWA community members are not included. If you try to activate exposure logging and your account is not allowlisted then you will see the error message "Cause 3". Other functionality in the app which does not rely on exposure logging can however still be tested.

  • The Storage is currently based on Encrypted Shared Preferences and SQL Cipher (SQLite) - this could change in the future

  • Test Coverage is generally low and needs to be improved. We appreciate your help here!

  • In General every TODO comment within the code or the documentation can be regarded as an issue. You are free to tackle the TODOs anytime!

  • We are aware of the Play Store Limitations of GMS.

  • Without your own server instance (e.g. a local Docker setup), you will not be able to test the Application. For help, please refer to the server implementation.

  • Strings including translations are provided and approved by the UA team. For suggestions / findings please open a dedicated issue.

Architecture & Documentation

The full documentation for the Corona-Warn-App is in the cwa-documentation repository. The documentation repository contains technical documents, architecture information, UI/UX specifications, and whitepapers related to this implementation.

Support & Feedback

The following channels are available for discussions, feedback, and support requests:

Type Channel
General Discussion
Feature Requests
Concept Feedback
Android App Issue
Backend Issue
Other Requests

How to Contribute

Contribution and feedback are encouraged and always welcome. For more information about how to contribute, the project structure, as well as additional contribution information, see our Contribution Guidelines. By participating in this project, you agree to abide by its Code of Conduct at all times.


The German government has asked SAP and Deutsche Telekom to develop the Corona-Warn-App for Germany as open source software. Deutsche Telekom is providing the network and mobile technology and will operate and run the backend for the app in a safe, scalable and stable manner. SAP is responsible for the app development, its framework and the underlying platform. Therefore, development teams of SAP and Deutsche Telekom are contributing to this project. At the same time our commitment to open source means that we are enabling -in fact encouraging- all interested parties to contribute and become part of its developer community.


A list of all public repositories from the Corona-Warn-App can be found here.


Copyright (c) 2020-2022 SAP SE or an SAP affiliate company.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.

You may obtain a copy of the License from here.

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the LICENSE for the specific language governing permissions and limitations under the License.

Please see the detailed licensing information via the REUSE Tool for more details.