Astronomer is described as 'Clickstream captures valuable user events and routes them to your favorite tools or data warehouse in real-time for analytics. With Astronomer, one snippet of code is all it takes to connect to any tool'. There are five alternatives to Astronomer, not only websites but also apps for a variety of platforms, including SaaS, Heroku, Self-Hosted solutions and Event Tracker. The best alternative is Segment, which is free. Other great sites and apps similar to Astronomer are Snowplow Analytics (Free, Open Source), Zenaton (Freemium), Prodlytic (Free) and CustomerLabs CDP (Freemium).
Segment is the analytics API you've always wanted. Instead of integrating with Google Analytics, Mixpanel, KISSmetrics, etc. individually, you integrate with a simple, clean API once and you can send your data to all of them.
CustomerLabs CDP helps marketers track, identify, segment & sync their customer data without writing a single line of code. Unify customer data across your marketing, sales & service channels. Create segments & sync them with your existing platforms.