Based on our record, PlantText seems to be more popular. It has been mentiond 2 times since March 2021. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
With respect to tools, planttext.com was my recent find and I really like it. With respect to drawing the diagrams, it improves as you do more and more architecture work. Most of the time, all you need is a block diagram to show the high level architecture, class design and sequence chart to show the implementation design/flow. Just keep it simple. Source: almost 2 years ago
I’ll just add https://planttext.com as the easiest way to get started with plantuml. Source: about 2 years ago
SequenceDiagram.org - Clean and fast online sequence diagram tool using scripting and Drag and Drop
UMLGraph - UMLGraph is a professional automated drawing tool that allows the designers the declarative specification and drawing of UML class and sequence diagram.
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.
Dia - Dia is a GTK+ based diagram creation program for GNU/Linux, MacOS X, Unix, and Windows, and is released under the GPL license.
WebSequenceDiagrams - WebSequenceDiagrams is a web-based application that allows the user to use a proprietary language to define sequence diagram.
yEd - 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.