Analyzify - Google tag manager and analytics app for your Shopify store
Skio - Sell subscriptions and give group discounts on Shopify
Shopgram - A free analyzing tool for exploring top Shopify stores
ReCharge - Pay for homes by the minute
MerchantSpring - Multi-channel analytics for Amazon, Walmart, eBay & Shopify
Chargebee - Chargebee lets you manage subscriptions and payments at scale, handle custom recurring billing scenarios, reduce subscription churn and simplify accounting.