Zooming support is also built into the Chart.
The whole product is available for free through the community license if you qualify (less than 1 million USD in revenue).
Note: I work for Syncfusion.
A lot depends on what you're looking for in a charting tool. Unfortunately, there's a really tricky tension between usability and expressiveness when it comes to visualization toolkits, meaning that if something is easy to set up, you probably won't be able to do much with it. If their standard plots are what you need, Google Charts are a great choice. If ...
I build for one of our projects various charts with chart.js (https://www.chartjs.org/). It is a good library for cool looking charts!
At some point we changed the charts for internal use to redash (https://redash.io/) because we needed more and more reports and also caching. You can install redash on your own server that has access to the corresponding ...
Have a look at plantuml(http://plantuml.com/) and their web server for some tests (http://www.plantuml.com/plantuml/uml)
PlantUML is a component that allows to quickly write :
Activity diagram (here is the legacy syntax)