LaTeXDraw might be a bit more popular than PlantText. We know about 2 links to it since March 2021 and only 2 links to PlantText. 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: about 2 years ago
I’ll just add https://planttext.com as the easiest way to get started with plantuml. Source: about 2 years ago
For the figures including TeX' annotation, both latexdraw and ipe, the later especially after the discovery of two tutorial videos (Introduction to Ipe drawing editor - Tools, Properties, & Snapping and How to create these figures in Ipe drawing editor). Both programs may be used either in Linux, Mac, Windows. For ipe, I like that the underlying LaTeX source code is embedded in the .pdf, so there is a way to... Source: over 1 year ago
If you are looking for application, then take a look at LaTexDraw. Source: over 1 year ago
UMLGraph - UMLGraph is a professional automated drawing tool that allows the designers the declarative specification and drawing of UML class and sequence diagram.
Inkscape - Inkscape is a free, open source professional vector graphics editor for Windows, Mac OS X and Linux.
Dia - Dia is a GTK+ based diagram creation program for GNU/Linux, MacOS X, Unix, and Windows, and is released under the GPL license.
PGF and TikZ - PGF/TikZ is a tandem of languages for producing vector graphics from a geometric/algebraic...
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.
draw.io - Online diagramming application