Unlimited Email Tracker - Track opens and clicks, set reminders and delays in Gmail
Google Fit SDK - Google Fit is an open ecosystem that makes it easy to store, access, and manage fitness data.
Mailtrack.io - The best email tracking solution I've found. Free
Accountable - Accountable is a platform designed to help organizations manage HIPAA compliance.
EmailTrackerPro - EmailTrackerPro is an email tracking and spam filter solution.
Lua - Powerful, fast, lightweight, embeddable scripting language