Markdown to PDF
You start with markdown — an .md file you already have, or text you paste in — and you finish with a PDF of the formatted document. Headings come out sized, lists indented, tables ruled, and code set in a monospaced face on its own tinted block. Formulas and diagrams are drawn into the page rather than left as the text that describes them. The result is an ordinary file that lands wherever your browser puts downloads, and it is a file rather than a link: there is no copy of your document anywhere for a link to point at.
The conversion happens on your own machine. Your document is opened, laid out and turned into a PDF inside the browser tab you already have open, and none of it is sent anywhere — there is no server to send it to. That is worth knowing before you convert a contract, a client's notes, or documentation that is not public yet, because most tools that do this job upload the file first and mention it afterwards, if at all. There is nothing to sign up for either, and nothing is kept when you close the tab except the documents your own browser is storing for you.
What happens at a page break
A screen has no pages and a PDF does, so every tool of this kind has to decide what to do when a table or a block of code reaches the bottom of one. The two usual answers are both bad: cut it in half, or let it run off the edge of the paper. This one moves the whole block onto the next page instead, so a table arrives with its header and all of its rows and a code block arrives entire. What that rests on, said plainly rather than implied: a fixed set of twenty documents, chosen between them to cover every kind of content this editor renders — long tables, wide tables, long code blocks, formulas, diagrams — goes through the built product before a release, and every one of them has to come out with nothing truncated and nothing split. That is a real test on real output, and it is also its limit. Twenty documents are not every document, and a page of content nobody anticipated may still surprise it; if yours does, your markdown is untouched and you can change it and convert again.
Three steps
Get your document into the editor: open an .md file from your machine, drag one onto the page, or paste the text in. Read the formatted side beside your markdown and fix anything that is not laying out the way you want, since what you see there is what the PDF will hold. Then choose Export, pick PDF, and your browser saves the file.
What it does not do
There are no settings to choose. The PDF comes out in one fixed layout and always in the light one, whatever theme you were working in, because the file gets read somewhere this editor is not — printed, attached to an email, opened on somebody else's machine. It converts the document you are looking at, one at a time, rather than a folder of them. And if an export fails for any reason, your document is untouched and you can try again.