Stylus Labs Write
This is a cool cross-platform application for authoring handwritten electronic documents. It can read/write SVG files directly, which can be embedded in web sites and read by other programs.
See also: How to embed handwritten content in your org-roam site
Some notes about Write, written in Write:
References
Home
This site is created using GNU Emacs and org-mode (specifically org-roam). There are also handwritten notes created with Stylus Labs Write.