To embed diagrams in GitHub markdown, diagrams can be saved as editable .png or .svg images and referenced directly using img tags, eg. ![Alt](images/someimage.png) with draw.io for GitHub at https://app.diagrams.net/?mode=github. To read and write files in Wikis, the desktop version from https://get.draw.io must be used due to limitations of the GitHub REST API.

Here is an example vector image:

Here is an example bitmap image:

View the diagram as an image: https://raw.githubusercontent.com/wiki/jgraph/draw.io/images/schema.png

View the diagram in fullscreen: https://app.diagrams.net/?lightbox=1#Uhttps%3A%2F%2Fraw.githubusercontent.com%2Fwiki%2Fjgraph%2Fdraw.io%2Fimages%2Fschema.png

Use the diagram as a template: https://app.diagrams.net/?#Uhttps%3A%2F%2Fraw.githubusercontent.com%2Fwiki%2Fjgraph%2Fdraw.io%2Fimages%2Fschema.png

Edit the diagram: https://app.diagrams.net/#Hjgraph%2Fdrawio-diagrams%2Fmaster%2Fdiagrams%2Fschema.xml (normal repository entry used, login required)