EventCatalog
Discover, Explore and Document your Event Driven Architectures.
PlantUML
Easily create beautiful UML Diagrams from simple textual description. There are also numerous kind of available diagrams. It's also possible to export images in PNG, LaTeX, EPS, SVG.
Software architecture tools
The best free and paid software architecture diagramming and design tools
Sparx Systems
Make your vision a reality with fast, intuitive modeling & design for systems, software, processes and architectures.
Architectural Decision Records
Homepage of the ADR GitHub organization
C4 Model
The C4 model for visualising software architecture
The Architecture of Open Source Applications
The Reactive Manifesto