Firebase + AdMob + RevenueCat Setup for Flutter

Prerequisites

• Firebase project created (firebase projects:create or Console)
• Billing account linked (gcloud billing projects link <project> --billing-account=<id>)
• flutterfire CLI installed (dart pub global activate flutterfire_cli)
• Debug keystore SHA-1 fingerprint obtained

Step 1: Get SHA-1 Fingerprint

# Windows (Chinese locale will mislabel — MD5 line is actually SHA-1)
keytool -list -v -keystore "%USERPROFILE%\.android\debug.keystore" -alias androiddebugkey -storepass android

# Verify: SHA-1 = 20 bytes (40 hex chars with colons = 59 chars)
# SHA-256 = 32 bytes (64 hex chars with colons = 95 chars)