Mobile development requires various services. AWS intends to ease the work of mobile developers by offering various services, including mobile-testing services, authentication services, and others. These services are described in the following list:

• AppSync: This is a service for web and mobile app developers. This service ensures the automatic updating of data for web and mobile applications in real time. If a user is offline, the data is updated as soon as the user comes online. AppSync uses an open standard query language called GraphQL. Using GraphQL, applications can request data from the cloud. AppSync is also very useful for developing a collaborative application that depends on the real-time updating of shared data. It can also be used in applications where data is sourced from various channels. AppSync's role and function are shown in the following diagram: 

• AWS Device Farm: This is an app-testing service. This service allows apps that have been developed in Android, iOS, or on the web to be tested against many devices. The user can select their choice of real phones and devices. AWS Device Farm allows direct access to these private devices from the host machine. This is similar to attaching devices directly to the host machine. The device screen is displayed on the browser. The user can then interact with the device screen and test the new functionality or reproduce bugs.
• Amazon Cognito: Cognito is a service for mobile and web app developers. Cognito provides an easy way for applications to add users, handle user sign in, and ensure that there is access control. Cognito also supports user login using any social identity providers, such as Facebook, Google, Amazon, and enterprise identity providers, such as Microsoft AD. If they use Amazon Cognito, users can create their apps without worrying about authentication, which will be taken care of by Amazon Cognito.