Which tools do you use to create diagrams?

Creates diagrams from textual descriptions! It provides a unified API with support for BlockDiag, BPMN, Bytefield, C4 (with PlantUML), Ditaa, Erd, GraphViz, Mermaid, Nomnoml, PlantUML, SvgBob, UMLet, Vega, Vega-Lite, WaveDrom

Draw SVG flow charts from simple text representations of the diagrams.

Excalidraw is a whiteboard tool that lets you easily sketch diagrams that have a hand-drawn feel to them.