draw.io - Online diagramming application
Kissflow - Kissflow is a workflow tool & business process workflow management software to automate your workflow process. Rated #1 cloud workflow software in Google Apps Marketplace.
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.
ProntoForms - ProntoForms is a mobile business solutions application, converting paper forms onto any tablet or mobile device.
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.
Nintex - Cloud-based digital workflow management automation platform