Bookmarklet: save webpage as clean Markdown file.

turndown.bookmarklet.js

javascript: Promise.all([
	import('https://esm.run/turndown'),
	import('https://esm.run/@mozilla/readability'),
	import('https://esm.run/turndown-plugin-gfm')
	]).then( ([
		{default: Turndown},
		{Readability},
		{gfm}]) => {
	const a=document.createElement('a'),
		options = {classesToPreserve: ['block-code',]},
		td = new Turndown({codeBlockStyle:'fenced'}),
		ra = new Readability(document.cloneNode(true), options).parse();
	
	td.use(gfm);
	let md = td.turndown(ra.content);
	md += `\n\n[original]: ${document.location.href} "${ra.title}"\n`;
	md = unescape(encodeURIComponent(md));
	a.href=`data:text/markdown;base64,${btoa(md)}`;
	a.download=ra.title.replace(/\s+/g,"-")+".md";
	a.click();
})

Minified version:

javascript:Promise.all([import('https://esm.run/turndown'),import('https://esm.run/@mozilla/readability'),import('https://esm.run/turndown-plugin-gfm')]).then( ([{default: Turndown},
{Readability},{gfm}])=>{const a=document.createElement('a'),options={classesToPreserve:['block-code',]},td=new Turndown({codeBlockStyle:'fenced'}),
ra=new Readability(document.cloneNode(true)).parse();td.use(gfm);let md=td.turndown(ra.content);md+=`\n\n[original]: ${document.location.href} "${ra.title}"\n`,md=unescape(encodeURIComponent(md));a.href=`data:text/markdown;base64,${btoa(md)}`;a.download=ra.title.replace(/\s+/g,"-")+".md";a.click();})