Janvas documents

The three files

Format	What it is	What it carries
`.ja`	the document: JSON text	the node tree, the working images inside the document, the document fonts (those extracted from PDFs)
`.jaz`	the package: a zip archive	the document, the images as files, the fonts, a thumbnail; optionally the photo originals and the installed fonts the texts use
`.json`	the same format as `.ja`, under its old name	it opens; "Save" overwrites it where it is, "Save as…" suggests `.ja`

It is much smaller than the .ja: the images are stored in it as compressed files, not as text.
It carries a thumbnail of the active page (or of the drawing).
With the photo originals inside, when you reopen it elsewhere the photos print at high resolution even without the files on disk.
With the local fonts inside, texts open correctly even on a computer that does not have them installed. Mind the font licenses.

With the app installed, .ja and .jaz have their own document icon in the Finder and open with Janvas.