SellerCenter - Store-oriented analytical tool
Site Rank Data - View historical rank information of websites via time series charts.
MerchantSpring - Multi-channel analytics for Amazon, Walmart, eBay & Shopify
HypeStat - HypeStat is free statistics and analytics service, where you can find information about every website.
Analyzify - Google tag manager and analytics app for your Shopify store
Q-Stats - Get free marketing insights for every question on Quora.