Akka - Build powerful reactive, concurrent, and distributed applications in Java and Scala
GoJS - GoJS is a JavaScript library for building interactive diagrams on HTML web pages. Build apps with flowcharts, org charts, BPMN, UML, modeling, and other visual graph types.
Tokio - Application and Data, Languages & Frameworks, and Concurrency Frameworks
mxGraph - mxGraph is a fully client side JavaScript diagramming library - jgraph/mxgraph
Finagle - Finagle is a protocol-agnostic RPC system.
jsPlumb - jsPlumb is an advanced, standards-compliant and easy to use JS library for building connectivity based applications, such as flowcharts, process flow diagrams, sequence diagrams, organisation charts, etc. More than just a diagram library.