StatCounter - StatCounter is a simple but powerful real-time web analytics service that helps you track, analyse and understand your visitors so you can make good decisions to become more successful online.
draw.io - Online diagramming application
Histats - Start tracking your visitors in 1 minute!
LucidChart - LucidChart is the missing link in online productivity suites. LucidChart allows users to create, collaborate on, and publish attractive flowcharts and other diagrams from a web browser.
AFSAnalytics - AFSAnalytics.
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.