What are some alternatives?
When comparing Code2Flow and PlantUML, you can also consider the following products
Graphviz - Graphviz is open source graph visualization software. It has several main graph layout programs.
draw.io - Online diagramming application
codepad - Very simple webpage with a simple textbox, a checkbox for selecting one of several languages and an...
yEd Graph Editor - yEd is a free desktop application to quickly create, import, edit, and automatically arrange diagrams. It runs on Windows, Mac OS X, and Unix/Linux.
Chart Mage - Generate sequence diagrams and flowcharts at lightning speed.
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.