Needing to draw an information system architecture so looking at my options.
- Edotor — Your Favorite Online Graphviz Editor - Graphviz is incredible (once you learn it) and was what I started with a couple of decades ago
- Excalidraw - love this one for quick “hand-drawn” diagrams
- tldraw - another good one for quick hand-drawn diagrams - new version in preparation available at tldraw at the time of writing
- Free Online Diagram Editor - another yEd clone
- Online FlowChart & Diagrams Editor - Mermaid Live Editor - check out the sample diagrams
- Project planning example - Markwhen - looks very good for Gantt charts
- Railroad Diagram Generator - not applicable here but looks good
- diagrams.net - superficially similar to yEd
- yEd Live - my favourite - have used the free Windows app version a lot
Recommend exporting as SVG (always) as this gives vector graphics quality and is compatible with HTML, Word, Powerpoint, etc.