draw.io: features, …

• https://about.draw.io/features/
• https://about.draw.io/features/examples/: mind maps, network diagrams, …
• https://en.wikipedia.org/wiki/Category:Diagramming_software

Draw.io is able to import and export diagrams as VSDX (Microsoft Visio’s OOXML-flavoured exchange format for drawings):

• http://jochen.hayek.name/wp/blog-en/2017/01/18/your-docx-or-your-xlsx-file-and-its-modified-timestamp/

On YouTube:

• https://www.youtube.com/watch?v=Z0D96ZikMkc
• https://www.youtube.com/watch?v=AZXPBf5UOrQ
• …

Draw.io Online User Manual:

• https://support.draw.io/display/DO/Draw.io+Online+User+Manual
• https://support.draw.io/display/DO/Part+2%3A+Working+with+Diagrams: has a couple of short tutorials
• …

Update 2018-04-17:

I like the diagrams I created using draw.io.

The intention was to export them as VSDX, but in the end Visio does not display them as intended. Very, very bad!