I’m currently working on and Editor and Viewer so deal with plantuml UML diagrams nicely. PlantUML is great, but far way from a simple user experience. Instead https://www.websequencediagrams.com is simple, but property and not not 100% free. Vizard aims to jump in here. Designed as a client side web application based on backbone.js, it will feature a view to load existing diagrams, as well as an editor to update those.
Storage integrations like local storage or even Github are planned. Alpha Preview: http://vizard.io

Soon more! Stay tuned and follow my development at https://github.com/rngtng/vizard

Disclaimer: vizard started as a 20% hacker project at SoundCloud.

Similar Projects:
https://texwriting.com/uml/new

Other Libraries:
https://libraries.io/search?q=plantuml