Check broken links in markdown

On a website I have a lot of markdown (educational) documents. These contains links to other sources (laws and regulations) that 'suddenly does not exist anymore'

It would be useful to be able to see if any links are broken on the site / in edit mode.

Any suggestion on how to do this? (maybe a markdown extension / javascript / portal_transform )

There are various browser extensions checking for broken links. But possibly not working in edit mode.

Would help a bit, but I have some Mac Safari users that 'might be a problem' (= they dont want to switch)