The Android platform provides a framework API that applications can use to interact with the underlying Android system. The framework API consists of: A core set of packages and classes. A set of permissions that applications can request, as well as permission enforcements included in the system

AppsFlyer applies advanced attribution analytics to generate high value app users from your mobile acquisition and retargeting campaigns. AppsFlyer’s SDK is lightweight and can be integrated in minutes. It tracks and measures all your user acquisition campaigns, no matter which ad network or agency is running it.

The Facebook SDK for Android is the easiest way to integrate your Android app with Facebook's platform. The SDK provides support for Login with Facebook authentication, reading and writing to Facebook APIs and support for UI elements such as pickers and dialogs.

The Facebook SDK for Android enables people to sign into your app with Facebook Login. When people log into your app with Facebook they can grant permissions to your app so you can retrieve information or perform actions on Facebook on their behalf.

Firebase is a platform developed by Google for creating mobile and web applications

Flutter is an open-source UI software development kit created by Google. It is used to develop applications for Android, iOS, Linux, Mac, Windows, Google Fuchsia, and the web from a single codebase.

Google Play services powers a broad set of SDKs on Android to help you build your app, enhance privacy and security, engage users, and grow your business. These SDKs are unique in that they only require a thin client library to be included in your app, as shown in figure 1. At runtime, the client library communicates with the bulk of the SDK's implementation and footprint in Google Play services.

Google Sign-In is a secure authentication system that reduces the burden of login for your users, by enabling them to sign in with their Google Account—the same account they already use with Gmail, Play, Google+, and other Google services. Google Sign-In is also your gateway to connecting with Google’s users and services in a secure manner. You can give your users the opportunity to pay with Google Pay, share with their Google-wide contacts, save a file to Drive, add an event to Calendar, and more. Integrate Google’s user-centric APIs and services inside your app to help your users take action and convert.

Square helps millions of sellers run their business-from secure credit card processing to point of sale solutions. Get paid faster with Square.

Yalantis develops modular systems with core functionality that clients can quickly replicate, adjust, and integrate into business processes of various companies.