What is minimum version of Google Play Services to use Firebase?

Question

Background

I'm developing an app using Firebase features (Realtime Database, Firebase Messaging, Analytics, Crash Reporting and Auth [Facebook]). In my country, most of the users don't have wifi and rarely upgrade apps (including Google Play Services).

Question

1. As the title suggests, I would like to know the minimum version (the lowest). I'm also willing to remove some features if it will help to lower the Google Play Services version.

2. Do I need to check google play service version in my application code or will Firebase check for me?

Finding so far and I'm confused,

• This post say min version is 9.0
• This post say min version is 8.1.15
• This SO question say developer no need to check Google Play Services
• but, This doc say developer need to check Google Play Services

Answer 1

The most trustworthy site says 9.0

For a list of the libraries available for the different Firebase features, see Firebase libraries. The following features are now part of Firebase in the Google Play Services 9.0 SDK.

The current stable is 9.4.

https://firebase.google.com/support/releases