General
General-Purpose & Multi-Paradigm diagramming tools.
Mermaid
Markdown-inspired syntax for generating flowcharts, sequence diagrams, and charts.
PlantUML
Text-based language for creating UML diagrams and system architectures.
Graphviz
Open-source graph visualization software using the DOT language.
Graphviz DOT
Open-source graph visualization software using the DOT language.
D2
Modern, declarative diagram scripting language.
Diagrams.net
Open-source visual diagram editor engine (Draw.io).
Excalidraw
Virtual whiteboard tool for hand-drawn, sketch-style diagrams.
UMLet
Free, interactive UML diagram drawing tool.
TikZ
Programmatic graphics package for TeX/LaTeX.
Architecture
Software Architecture & Modeling tools.
C4-PlantUML
PlantUML macros and extensions for rendering the C4 software architecture model.
Structurizr
Tooling for visualizing and documenting software architecture based on the C4 model.
Nomnoml
Lightweight tool for drawing UML class diagrams from simple grammar.
Infrastructure
Network, Infrastructure & Layout diagramming tools.
BlockDiag
Block diagram generation tool.
ActDiag
Activity diagram generator.
NwDiag
Network diagram generator.
RackDiag
Server rack layout diagram generator.
PacketDiag
Network packet structure diagram generator.
SeqDiag
Sequence diagram generator.
Wireviz
Documentation tool for cables, wiring harnesses, and pinout diagrams.
Hardware
Hardware, Timing & Protocol diagramming tools.
WaveDrom
JavaScript/JSON-based digital timing diagram rendering engine.
Bytefield
Tool for generating network protocol and memory layout packet diagrams.
Symbolator
Schematic symbol generator from HDL (Hardware Description Language) code.
ASCII & Tools
ASCII Art, Text-to-SVG converters, and ecosystem aggregators.