Create Diagrams from Text

PlantUML

PlantUML is an open-source tool allowing users to create diagrams from plaintext language. Besides various UML diagrams, PlantUML has support for various other software development-related formats (such as Archimate, Block diagram, BPMN, C4, Computer network diagram, ERD, Gantt chart, Mind map, and WBD).

While this option doesn't give you nearly as many options as Visio, it is fast and creates decent-looking diagrams without having to spend hours aligning boxes and arrows. The other advantage is that the text file can be version-controlled. If your diagram isn't confidential, there are even some online tools that will render the diagram for you right from a website, such as PlantText.

C4 model for diagramming software architecture

If you're not already familiar with it, the C4 model is an "abstraction-first" approach to diagramming software architecture, based upon abstractions that reflect how software architects and developers think about and build software. The small set of abstractions and diagram types makes the C4 model easy to learn and use. Please note that you don't need to use all 4 levels of diagrams; only those that add value - the System Context and Container diagrams are sufficient for many software development teams.

C4-PlantUML combines the benefits of PlantUML and the C4 model for providing a simple way of describing and communicating software architectures – especially during up-front design sessions – with an intuitive language using open source and platform-independent tools.

The following is an example diagram generated by PlantUML with the C4 model: