When comparing UMLet vs PlantUml, the Slant community recommends PlantUml for most people. In the question“What are the best UML applications out there?” PlantUml is ranked 2nd while UMLet is ranked 6th. The most important reason people chose PlantUml is:
For example from Emacs, Sublime Text and so on. You can learn about integrations [here](http://plantuml.com/running).
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Open Source
GNU General Public License
Pro Many, many integrations
For example from Emacs, Sublime Text and so on. You can learn about integrations here.
Pro Easy create diagrams from text
There is even a Visual Basic Macro to draw UML diagrams in Word.
Pro Free/libre/open source (GPL)
Source code can be browsed here.
Pro Has online editors
Such as.
Pro sphinx-contrib extension for embedding into docs
sphinx-contrib extension on PyPi
Allows you to keep your UML definitions under VCS and include them inside generated documentation with ease.
Cons
Con Almost discontinued
Some users push fixes, but there isn't any real development flow.
Con Not user-friendly
Con The "plantUML-language" is a bit strange and hard to grasp for new people
Con Slow development due to it being mostly a one-man project
There’s been no recent contribution to the source forge project but from the administrator arnaud_roques. Future contribution might be difficult due to lacking code documentation.