Apple App Analytics - Apple's very own iTunes Connect App Analytics
Braavo Analytics - Essential app analytics for busy founders
AppMetrica by Yandex - Free ad tracking & full-stack app analytics for mobile apps.
CleverTap - CleverTap offers blazing fast analytics, powerful real-time segmentation, multi-channel messaging, A/B testing and personalization in one unified solution.
ProfitWell - SaaS Metrics for Stripe. Absolutely Free.
Qonversion - The subscription data platform for mobile-first companies